The effect of V, VCl3 and VC catalysts on the MgH2 hydrogen sorption properties

MgH2 based composites processed by mechanical alloying with the addition of 5 wt.% of V, VC and VCl3 were evaluated for their absorption/desorption hydrogen capacities at 300 and 350 °C. These composites were investigated by the following techniques: X-ray diffraction, XRD, Pressure–Composition Isotherms, PCI and Differential Scanning Calorimetry, DSC. It was observed that the addition of V, VC and VCl3 compounds improves hydrogen absorption and desorption kinetics in comparison to the MgH2. The MgH2-5 wt.% VCl3 composite showed the faster absorption kinetics which absorbed 6.0 wt.% of H2 in 7.5 min at 350 °C. The desorption activation energy of the composite containing VCl3 (47 kJ mol−1) is smaller than VC (63 kJ mol−1). This indicates that this catalyst is more effective to be used in hydrogen storage system.

• The samples, MgH2 + 5 wt.% x (x = V, VCl3 and VC), were obtained by mechanical milling.
• VCl3 showed to be a promising catalyst.
• A maximum capacity of 6.0 wt.% of H2 was attained in 7.5 min.