Designed synthesis of semi-embedded Pd over CeO2-ZrO2/Al2O3 as advanced three-way catalyst

For catalytic system consists of Pd as active component and CeO2-ZrO2/Al2O3 (CZ/A) as support, the dispersion and oxidation state of Pd species, which are crucial to the catalytic performance, are closely related to the metal-support interaction. In this work, Pd species were introduced into CZ/A system at different thermal treating stages of the support, which brought about different Pd-CZ interaction. The characterization results reveal that when CZ/A support was thermal treated at 300 degrees C prior to the introduction of Pd species, a special Pd/CZ/A catalyst with Pd species semi-embedded in CZ/A was acquired, which exhibits excellent thermal stability owing to the appropriate Pd-CZ interaction. During thermal aging process, encapsulation and aggregation of Pd species are effectively inhibited for Pd/CZ/A with semi embedded structure. Thus, higher dispersion, more oxidative Pd2+ species and larger amount of oxygen vacancies are maintained after aging, which consequently lead to its superior three-way catalytic performance. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.