engleski

Quasiclassical trajectory calculations of hydrogen absorption in the (NaAlH4)2Ti system on a model analytical potential energy surface

We performed a quasiclassical trajectory dynamics study on a model analytical 21-dimensional (7 active atoms) potential energy surface (PES) to examine in detail the mechanism of the hydrogen absorption in a simple (NaAlH4)2Ti model system. The reaction involves a capture of H2 by the Ti centre and formation of the (hapto2-H2)Ti(NaAlH3)2 coordination complex containing the side-on bonded dihydrogen ligand. The calculated rate constant corresponds to a very fast capture of H2 by the Ti coordination sphere without a demonstrable barrier. This implies that this step is not the rate-determining step in the complex multi-step process of the NaAlH4 recovery. The model analytical PES captures the essence of this reaction well and the corresponding energy contours compare favourably to those based on the all-atom hybrid density functional theory calculations.

hydrogen storage; sodium alanate; catalysis; transition metal doping; density functional theory; quasiclassical trajectory study; potential energy surface

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