Reversible hydrogen storage properties of NaAlH4 enhanced with TiN catalyst

Abstract

Hydrogen storage properties of commercial NaAlH4 doped efficient TiN catalyst have been systematically investigated. The dehydrogenation and reversibility of the 2mol% TiN-doped NaAlH4 (2%TiN–NaAlH4) system have been studied. It is found that TiN catalyst improves the dehydrogenation kinetics and decreases the dehydrogenation temperature of NaAlH4. Interestingly, the onset dehydrogenation temperature of 2%TiN–NaAlH4 system gets lowered to about 130.0°C with a faster kinetics, and the dehydrogenation rate reaches a maximum value at 183.5°C. The apparent activation energy for the first and the second dehydrogenation step of TiN–NaAlH4 system is estimated to be 91.70kJmol−1 and 99.93kJmol−1, respectively. The dehydrogenation and hydrogenation behaviors of 2%TiN–NaAlH4 are investigated under different hydrogen pressures using high-pressure differential scanning calorimetry (HP-DSC). The 2%TiN–NaAlH4 system exhibits excellent reversibility at moderate conditions. Moreover, the dehydrogenation and hydrogenation processes of the 2%TiN–NaAlH4 system are also discussed.