NANOSTRUCTURED ALUMINA CERAMIC MEMBRANES FOR GAS SEPARATION

Abstract

Nanostructured alumina ceramic templates have been fabricated by anodizing annealed high-purity aluminium foil. Pore diameter, pore separation and thickness in these alumina ceramics can be controlled using a range of acid electrolytes and anodizing voltage profiles. Thermal development of the structure of these robust and optically clear templates have been compared using XRD, thermal analysis and 27 Al MAS NMR techniques, showing that species substituted in the alumina lattice from decomposition of the acid electrolyte play a major role in determining the chemical and physical stability of the ceramic template at elevated temperatures. Deposition of ultrathin palladium films on the surface of these alumina templates creates robust membranes that enable hydrogen separation from mixed gas streams at elevated temperatures. Gas permeability measurements through these membranes as a function of temperature have demonstrated their very high selectivity for hydrogen.