Role of M~(n+) cations in the redox and oxygen transfer properties of BaM_xAl_(12-X)O_(19-δ) (M = Mn, Fe, Co) nanomaterials for high temperature methane oxidation

摘要

BaM_xA_(12-x)O_(19-δ) (M = Mn, Fe, Co, x = 1, 2) hexaaluminate nanomaterials were successfully prepared using the ARS (Activated Reactive Synthesis) process, a top-down and solvent free original synthesis route. The crystal sizes of the nanomaterials range at 24 ± 2 nm, which allows them to display high surface area (from 60 to 100 m~2 g~(-1)). The role of M~(n+) cations in the redox and oxygen transfer properties of the nanomaterials was studied by H2-TPR and ~(18)O/~(16)O isotoplc exchange, respectively. The nature of the transition metal as well as its content is observed to play a key role in the oxygen transfer properties. The catalytic properties of the nano-hexaaluminates, evaluated for methane oxidation, a reaction involving severe conditions (high temperature), resulted from multiple factors including oxygen transfer properties and transition metal valence and concentration on the surface.