Improvement of three-way catalytic performance by optimizing ceria and promoters in Pd-only catalyst prepared by sol-gel method

Pd-only three-way catalysts containing bulk ceria and/or stabilized ceria (CeO₂-ZrO₂) and promoters such as V and Zr were prepared by sol-gel method and characterized by three-way catalytic performances test, X-ray diffraction, BET surface area and pore size distribution, temperature-programmed reduction and oxygen storage capacity measurement. It was found that bulk and stabilized ceria should be physically mixed to improve the three-way catalytic performance. Optimally formulated physical mixture catalyst showed excellent activity and thermal stability even after aging at 1000°C for 50 h, which seemed to be ascribed to the significant suppression of ceria sintering by anchoring effect, and to the separation of easily agglomerating ceria from palladium by physical mixing.