Effect of Ni and SAPO-34 co-additive on enhancing hydrogen storage performance of MgH2

The hydrogen storage performances of MgH 2 improved by the addition of Ni and SAPO-34 were studied in detail. The mixture of MgH 2 with Ni and SAPO-34 was a physical reaction as shown by the X-ray diffraction (XRD) results. The SAPO-34 and Ni were uniformly distributed on the surface of MgH 2 . The thermodynamic and kinetic properties of 90MgH 2 /5Ni/5SAPO-34 were investigated by differential scanning calorimetry (DSC) and pressure-composition-isothermal (PCI) methods. The results showed that the dehydrogenation activation energy of 90MgH 2 /5Ni/5SAPO-34 decreased by 64.3 kJ/mol compared with that of MgH 2 . In addition, the relationship between the value of dehydrogenation heat and hydrogen content was also investigated by in-situ calorimetry. The enthalpy value of each sample in the dehydrogenation processes were calculated by in-situ calorimetry measurement. The dehydrogenation enthalpies of as-milled MgH 2 and 90MgH 2 /5Ni/5SAPO-34 were 63.2 kJ/mol H 2 and 53.6 kJ/mol H 2 , respectively. Thus, the co-doping of Ni and SAPO-34 contributed significantly to decrease the thermodynamic stability and improve the hydrogen sorption kinetic properties of MgH 2 .