کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1279435 | 1497665 | 2008 | 7 صفحه PDF | دانلود رایگان |
LiBH4LiBH4–MgH2MgH2 composite exhibits excellent reversible hydrogen capacity, but it still presents high decomposition temperature over 350∘C and sluggish kinetics. For the purpose of optimizing its reaction performance, Nb2O5Nb2O5 was doped into this composite as a catalyst to form a more destabilized and reversible composite system. It possesses a maximum capacity of approximately 6–8 wt% hydrogen releasing below 400∘C and could be hydrogenated to 5–6 wt% hydrogen capacity at 400∘C under 1.9 MPa. XRD and SEM analysis revealed that NbH2NbH2, formed and highly dispersed in the composite, played a key role in changing the original path and resulted in the formation of an intermediate compound (MgB2)(MgB2) in the milling process. The hydrogen storage capacity of the LiBH4LiBH4–MgH2(massratio,1:2)+16wt%Nb2O5 composite decreased gradually during the dehydrogenation/hydrogenation cycles and still maintained 5.16 wt% in the third dehydrogenation process. The activation energies EAEA of LiBH4LiBH4–MgH2MgH2 (mass ratio, 1:2) with 16 wt% Nb2O5Nb2O5 and without Nb2O5Nb2O5 were estimated to be 139.96 and 156.75kJmol-1 by Kissinger method. It indicates that the additive Nb2O5Nb2O5 can decrease the activation energy of LiBH4LiBH4–MgH2MgH2 composite.
Journal: International Journal of Hydrogen Energy - Volume 33, Issue 1, January 2008, Pages 74–80