The present work concerns the catalytic effect of VNbO5, a ternary oxide prepared via a solid-state route, on the sorption performance of MgH2. Three doped systems, namely 5, 10 and 15 wt% VNbO5-MgH2have been prepared by ball milling and thoroughly characterized. Hydrogen sorption, evaluated by temperature programmed desorption experiments, revealed a significant reduction of the desorption temperature from 330 Â°C for the un-doped sample (prepared and tested for comparison) to 235 Â°C for the VNbO5-doped sample. Furthermore, more than 5 wt% of hydrogen can be absorbed in 5 minutes at 160 Â°C under 20 bar of hydrogen, which is remarkable compared to the 0.7 wt% achieved for the un-doped system. The sample doped with 15 wt% of additive, showed good reversibility: over 5 wt% of hydrogen with negligible degradation even after 70 consecutive cycles at 275 Â°C and 50 cycles at 300 Â°C. The kinetics analysis carried out by Kissinger's method exhibited a considerable reduction of the activation energy for the desorption process. Finally, pressure-composition-isotherm experiments conducted at three different temperatures allowed estimating the thermodynamic stability of the system and shed light on the additive role of VNbO5.
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|Titolo:||Remarkable hydrogen storage properties of MgH2doped with VNbO5|
|Data di pubblicazione:||2018|
|Appare nelle tipologie:||1.1 Articolo in rivista|