Thesis - Oztek_Muzaffer_T_200508_MA

hydrogen capacity was not reproducible due to commercial unavailability of
manufacturing equipment supplies.
Zirconium based alloy ZrCo was reported to absorb less than 0.1% hydrogen at
473 K [31]. ZrNi was reported to absorb approximately 3% hydrogen at room
temperature, with a considerable hysteresis during desorption, and the reaction between
ZrNi and H 2 was completed in more than 55 hours [32]. Zr 3 Al 2 , ZrV 2 and ZrNi particle
beds were reported to rapidly and selectively remove hydrogen from a hydrogen/argon
stream, eventually reducing the hydrogen content from 10% to 1 ppm by low temperature
H 2 adsorption [19].
1.3. LaNi 5
After a review of several the candidate materials, Mg 2 Ni, VTiNi and LaNi 5 were
selected for study. Emphasis was placed on LaNi 5 , as will be discussed in this thesis. It
was selected because it exhibits excellent properties for use in a successful hydrogen
recovery-storage-delivery system [2]. LaNi 5 rapidly reaches equilibrium with hydrogen,
even at low pressures and temperatures. Also, the hydriding and dehydriding processes
are reversible at H 2 partial pressures close to atmospheric [28]. LaNi 5 exhibits low
hysteresis and is not strongly affected by gaseous impurities or by oxidation. On
compounds such as Nb, V, Ta, FeTi, oxidation creates a barrier for the interaction and
dissociation of H 2 molecules. On the surface of LaNi 5 , the highly reactive La reacts with
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