Inhibition of Metal-Support Interactions by Rare-Earth Doping in Palladium/Ceria Zirconia Three-Way Catalysts.

The impact of rare-earth (RE) doping in ceria-zirconiacritical for enhancing thermal stability and optimizing redox propertieson surface palladium (Pd) behavior has been investigated. RE doping was found to weaken metal-support interactions, leading to increased Pd mobility, with notable effects on oxygen storage capacity and light-off performance under model exhaust conditions. The mobility and redox characteristics of Pd were assessed through in situ thermal experiments using X-ray absorption spectroscopy at the Pd K-edge and synchrotron powder diffraction. Complementary Ce K-edge EXAFS and Rietveld refinements confirmed the structure and composition of the doped ceria-zirconia material. Deactivation studies and lifetime prediction are essential for commercial catalysts, particularly for three-way catalysts (TWCs) designed for decade-long operation. To probe long-term stability, in situ thermal treatments were conducted to induce separation of the metastable ceria-zirconia solid solution. These accelerated thermal aging treatments were then compared with a prolonged, seven week aging protocol, and regular in situ synchrotron PXRD measurements provided insights into the phase separation process. The influence of thermal aging on metal-support interactions was further assessed through catalytic performance testing.