Promotion of CeO2-ZrO2-Al2O3 composite by selective doping with barium and its supported Pd-only three-way catalyst

In this work, CeO2-ZrO2-Al2O3 (CZA) composites promoted by selective doping with Ba were prepared by simple coprecipitation method. The structural characterization results reveal that with small doping amount (≤6 wt%), Ba can preferentially combine with Al;bsubesubbsubesub and acts as a stabilizer, which could facilitate the formation of more homogeneous CZ solid solutions. When the content of BaO increases to 8 wt%, besides the portion combined with Al;bsubesubbsubesub, the remnant Ba would enter into the lattice of CeO;bsubesubbsubesub to form a ternary CeO;bsubesubbsubesub-BaO solid solution, thus further improved oxygen mobility is obtained. However, excessive doping amount (10 wt%) brings about self-aggregation of BaO, which seriously deteriorates the structure of the CeO;bsubesubbsubesubbsubesubbsubesub-BaO composite. The XPS results demonstrate that with optimal doping content of BaO (8 wt%), the supported catalyst Pd/CZAB8 possesses highest surface Pd and Ce;bsupesup concentrations, which consequently leads to improved reducibility and catalytic performance. Furthermore, the synergistic effect between CeO;bsubesubbsubesub-BaO and BaO-Al;bsubesubbsubesubcurren; helps improve the thermal stability of Pd/CZAB8. Thus, superior textural, structural, morphological and reduction properties along with enhanced three-way catalytic performance are obtained for aged Pd/CZAB8a.

Duke Scholars

Author Li Lan Molecular Genetics and Microbiology