Controllable synthesis of zone-distributed Pd over CeO2-ZrO2/Al2O3 as advanced three-way catalyst

Two optimally designed catalysts (Ce0.7Zr0.3O2/Pd/Al2O3, Pd/Ce0.7Zr0.3O2/Pd/Al2O3) were synthesized and compared with conventional Pd/Ce0.7Zr0.3O2/Pd/Al2O3. The characterization results reveal that for Pd/Ce0.7Zr0.3O2/Pd/Al2O3, Pd species undergo severe agglomeration and encapsulation during thermal aging process, leading to dramatic catalyst deactivation. While for the two optimized catalysts, some Pd species initially distributed on Al2O3 would migrate to the surface of CexZr1-xO2(CZ) grains upon aging treatment, resulting in enhanced Pd-CZ interaction, thus the two aged samples possess higher dispersion, larger amount of oxidized Pd2+ species and more oxygen vacancies compared with conventional Pd/Ce0.7Zr0.3O2/Pd/Al2O3-a. Consequently, modified reducibility and improved three-way catalytic performance are obtained, especially for Pd/Ce0.7Zr0.3O2/Pd/Al2O3-a. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.