Advanced Electron Microscopy Characterisation of Al-O Coordination in Catalyst Supports

Abstract

Performance of alumina supported catalyst systems are significantly affected by how the tetrahedral (Al-O4) and octahedral (Al-O6) coordination are mixed and blended with each other. Characterisation of Al-O coordination is thus important to understand how catalysts interact with alumina at the microscopic level. Here we report the application of two advanced electron microscopy techniques on Al-O coordination. The first technique is Electron Energy Loss Spectroscopy (EELS) that can reveal detailed electronic structure profile of Al valence band to analyse how Al is coordinated by oxygen. The second technique is Pair Distribution Function (PDF) based on Electron Diffraction (ED), employed to measure Al-O bond lengths associated with the coordination geometry.