CeO2–ZrO2–Al2O3 Modified by Selective Doping with SrO for Improved Pd-Only Three-Way Catalyst

Abstract

Composite CeO₂–ZrO₂–Al₂O₃ (CZA) modified by selective doping with SrO was prepared by simple coprecipitation method. The characterization results reveal that the structural property of the modified sample is fundamentally different from that of undoped CZA, the doped SrO can selectively combine with Al₂O₃ and act as a stabilizer, meanwhile homogeneous CZ solid solution is formed which appears insusceptible to Al₂O₃. Consequently more lattice defects are created in CZAS, which facilitate the improvement of oxygen mobility. The UV–Vis DRS and XPS results demonstrate that after doping with SrO, the supported catalyst Pd/CZAS possesses higher surface Pd and Ce³⁺ concentrations, which consequently leads to improved reducibility and catalytic performance. Furthermore, the synergistic effect between CeO₂–ZrO₂ and SrO–Al₂O₃ helps improve the thermal stability of Pd/CZAS. As a result, after aging treatment, Pd/CZASa still maintains improved structural, textural, morphological and reduction properties along with enhanced three-way catalytic performance.