Inclusion of CoTiO3 to ameliorate the re/dehydrogenation properties of the Mg–Na–Al system

Abstract

For the first time, the MgH2–NaAlH4 (ratio 4:1) destabilized system with CoTiO3 addition has been explored. The CoTiO3-doped MgH2–NaAlH4 sample begins to dehydrogenate at 130 °C, which is declined by 40 °C compared to the undoped MgH2–NaAlH4. Moreover, the de/rehydrogenation kinetics characteristics of the CoTiO3-doped MgH2–NaAlH4 were greatly ameliorated. With the inclusion of CoTiO3, the MgH2–NaAlH4 composite absorbed 5.2 wt.% H2, higher than undoped MgH2–NaAlH4. In the context of dehydrogenation, the CoTiO3-doped MgH2–NaAlH4 sample desorbed 2.6 wt.% H2, almost doubled compared to the amount of hydrogen desorbed from the undoped MgH2–NaAlH4 sample. The activation energy obtained by the Kissinger analysis for MgH2 decomposition was significantly lower by 35.9 kJ/mol than the undoped MgH2–NaAlH4 sample. The reaction mechanism demonstrated that new phases of MgCo and AlTi3 were generated in situ during the heating process and are likely to play a substantial catalytic function and be useful in ameliorating the de/rehydrogenation properties of the destabilized MgH2–NaAlH4 system with the inclusion of CoTiO3.

Keywords

• Destabilize system
• Magnesium hydride
• Sodium alanate
• Hydrogen storage
• Additive