Role of Mn+ cations in the redox and oxygen transfer properties of BaMxAl12−xO19−δ (M = Mn, Fe, Co) nanomaterials for high temperature methane oxidation

Abstract

BaM_xAl_12−xO_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 m² g⁻¹). The role of Mⁿ⁺ cations in the redox and oxygen transfer properties of the nanomaterials was studied by H₂-TPR and ¹⁸O/¹⁶O isotopic 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.