Improved dehydrogenation of TiF₃-doped NaAlH₄ using ordered mesoporous SiO₂ as a codopant

A study of the influence of mesoporous SiO₂ on the dehydrogenation of NaAlH₄ and TiF₃-doped NaAlH₄ revealed that the amount of hydrogen evolved is 3.8 wt% for the pristine NaAlH₄ and around 4.2 wt% for the TiF₃-doped NaAlH₄, but increases to 4.9–5.0 wt% once the samples are doped with mesoporous SiO₂ in the temperature range of 100–350 °C. A favorable synergistic effect on the NaAlH₄ dehydrogenation is achieved as mesoporous SiO₂ is added as a codopant along with TiF₃, which is associated with the nanosized pores and high specific surface area of mesoporous SiO₂. The catalytic mechanism of mesoporous SiO₂ is more physical than chemical relative to the catalytic mechanism of TiF₃.