Analysis of transition alumina structures using HRTEM

The transition aluminas are important materials used as catalysts, co-catalysts, catalyst supports, and adsorbents, γ-alumina is used in catalysis because it has a high surface area and an inherent defect structure. Much of the special surface chemistry is attributed to defect acid sites. These sites apparently occur during the dehydroxyilation of the oxyhydroxides which are their precursors. The structure of γ-Al2O3 is not well understood; most of the previous structure analysis has used powder x-ray diffraction. In this study high resolution transmission electron microscopy (HRTEM) and selected area diffraction (SAD) were used to investigate the structure and the defect nature of the aluminas.