Effect of TiO2 + Nb2O5 + TiH2 Catalysts on Hydrogen Storage Properties of Magnesium Hydride

Abstract

Magnesium hydride (MgH2) is a prospective material for the storage of hydrogen in solid materials. It can also be envisaged for thermal energy storage applications since it has the potential to reversibly absorb hydrogen in large quantities, theoretically up to 7.6% by weight. Also, MgH2 is inexpensive, abundant, and environmentally friendly, but it operates at relatively high temperatures, and the kinetics of the hydrogenation process is slow. Mechanical milling and the addition of catalyst can alter the activation energy and the kinetic properties of the MgH2 phase. It is known that the addition of titanium hydride (TiH2) lowers the enthalpy and enhances the absorption of hydrogen from MgH2, titanium oxide (TiO2) enhances the desorption of hydrogen and niobium oxide (Nb2O5) enhances the absorption of hydrogen. In this work, the influences of the catalysts, as mentioned above on the properties of MgH2, were studied. The samples were analyzed in terms of crystal and microstructure as well as hydrogen storage properties using a pressure-composition isotherm (PCT)measurement. It has been found that the simultaneous addition of the three catalysts enhances the properties of MgH2, lowers the activation energy and operating temperature, increases the rate of intake and release of hydrogen, and provides the largest gravimetric hydrogen storage capacity.