Prospect of Using Nanoalloys of Partly Miscible Rhodium and Palladium in Three-Way Catalysis

Alloys of partly miscible metals attract a growing attention due to their unique physicochemical properties. Palladium–rhodium solid solution was synthesized using a multi-metal single precursor concept. Pd–Rh/γ-Al2O3 catalyst was prepared by an impregnation of the support with a solution of a precursor containing organic ligand. The Pd:Rh ratio in the alloy was 3:2. The samples were characterized by a powder X-ray diffraction analysis, a transmission electron microscopy, electron paramagnetic resonance and photoluminescence spectroscopies. The catalytic behavior of the samples was examined in CO oxidation reaction under prompt thermal aging conditions. The stability of the bimetallic catalyst was found to be improved if compare with monometallic reference samples. Mutual anchoring of palladium and rhodium prevents both the surface migration of Pd particles followed by their agglomeration and the diffusion of rhodium ions into the bulk of alumina support. Improved metal-support interaction for the studied system was found to be facilitated by presence of electron donor sites on the surface of the support.