Optimally designed synthesis of advanced Pd‐Rh bimetallic three‐way catalyst

For Pd-Rh bimetallic three-way catalysts, appropriate Pd-Rh interaction is of significant importance to the catalytic activity. In this work, an optimally designed approach was utilized to synthesize Pd-Rh bimetallic catalyst supported on CeO2-ZrO2-Al2O3 (Rh/CZ/Pd/A), which was compared with the conventional catalysts prepared by mechanical mixing method and co-impregnation technique. In Rh/CZ/Pd/A, Rh species are distributed on the external surface of CZ, while Pd species are distributed in the inner layer. Upon the application of the hydrothermal aging treatment, Pd species undergo migration to the outer sphere of CZ grains. Meanwhile, modified Pd-Rh interaction and metal-support interaction are obtained, which are efficient for stabilizing PdO and Rh2O3 at high temperatures, as well as suppressing the deactivation of Rh species by diffusing into the support. Overall, smaller size, better dispersion, along with the higher oxidation state of Pd species and the more reducible oxidation state of Rh species are maintained for Rh/CZ/Pd/A-a. Consequently, improved three-way catalytic activity is achieved for Rh/CZ/Pd/A especially after the hydrothermal aging treatment.