In situ XAFS Characterization of Supported Homogeneous Catalysts

Heterogenization of homogeneous catalysts explores the cross-fertilization of homogeneous and heterogeneous catalysts to combine most of their advantages. The molecular dispersion of active sites in these materials limits the application of conventional spectroscopic techniques utilized for the characterization of heterogeneous catalysts. The X-ray absorption spectroscopy is the most suitable tool to characterize the molecular species present in these catalysts because this technique is sensitive to short-range structural orders, element-specific and amenable to in situ studies. X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) studies for selective examples of supported homogeneous catalysts are reviewed. Supported liquid phase catalysts (supported Wacker-type catalysts for CO oxidation), intercalated homogeneous catalysts, supported metal complexes for the olefin polymerization and tethered homogeneous catalysts are included.