Iron-Oxide Supported Gold Catalysts Derived from Gold-Phosphine Complex Au(PPh3)(NO3): State and Structure of the Support

Abstract

Iron oxide supported gold catalysts were prepared by supporting the Au-phosphine complex Au(PPh3)(NO3) onto various iron oxide supports. Among the prepared catalysts only the use of amorphous as-precipitated iron hydroxide Fe(OH)*3as a support for Au(PPh3)(NO3) allowed us to obtain the tremendously active catalytic material for low-temperature CO oxidation. The supports and the Au catalysts were characterized by BET, SEM, XRD, FT-IR, XPS, and Raman. Initial structures of the employed supports were found to influence dramatically the gold particle size and the catalytic activity. The most active catalyst consisted of small gold particles and poorly crystallized iron oxide support with a mixture of α-Fe2O3and γ-Fe2O3. The γ-Fe2O3formation occurred by the presence of the PPh3as a ligand for gold. The presence of γ-Fe2O3influenced positively the catalytic activity of the Au-containing samples.