Nature and Role of Ti Species in the Hydrogenation of a NaH/Al Mixture

Abstract

A mixture of TiF 3 -doped NaH/Al was directly used as the starting material, and hydrogenated singly in order to study the chemical state and role of Ti species in hydrogenation. X-ray absorption spectroscopy shows that Ti 3+ was essentially reduced to Ti 0 and formed Ti−Al clusters during the doping, i.e. the ball-milling process. The local environment around Ti atoms in the clusters became homogeneous and ordered after hydrogenation at 100−140 °C. The Ti−Al clusters are believed to be the catalyzing agent for the dissociation of the hydrogen molecule and the subsequent formation of the hydride.