(670e) Multi-Technique Microscopy Use for Identification of Active Sites in Supported Catalysts

A primary focus of catalytic research has been the identification and study of catalytic sites.
Since active sites are by necessity of atomic scale tools for their identification must therefore have atomic-scale resolution.
The mainstays of catalytic microscopy XRD, SEM, and TEM while extremely useful are limited to resolutions greater than 1 nm.
EXAFS is another technique used for catalysis research and can yield sub-nm resolution of catalytic materials.
It does however require massive infrastructure as well as careful and intricate analysis.
In recent years the growing availability of Aberration Corrected TEM(ACTEM) has allowed for atomic-level resolution and an unprecedented avenue for understanding the true identity and structure of the catalytically active site.

Careful use and comparison of these several microscopy techniques in combination with reactivity tests have suggested that clusters of 1-to-5 atoms of palladium supported on γ-Al₂O₃ and ZnO are involved in CO oxidation, the water-gas shift and reverse water-gas-shift reactions, and alcohol steam reforming.