Optimized synthesis of highly thermal stable CeO2-ZrO2/Al2O3 composite for improved Pd-only three-way catalyst

As is well known, impregnation of precursors of Ce and Zr onto as-prepared Al2O3 powders is a commonly used approach to prepare CeO2-ZrO2/Al2O3 composite. In this work, a highly thermal stable CeO2-ZrO2/Al2O3 composite was synthesized by modifying the conventional preparation procedure, i.e., the precursor of Al2O3 thermal treated at comparatively lower temperature (200 degrees C) was applied to conduct the impregnation process. The characterization results of the supported Pd-only three-way catalysts reveal that in themodified sample, stronger interaction between CeO2-ZrO2 and Al2O3 is achieved, which consequently gives rise to higher thermal stability of the catalyst. Upon hydrothermal aging treatment, only slight aggregation of the CeO2-ZrO2 and Al2O3 particles takes place, meanwhile phase transformation of gamma-Al2O3 and phase separation of CeO2-ZrO2 component are successfully suppressed. As a consequence, Pd species supported on the modified CeO2-ZrO2/Al2O3 composite remain finely dispersed, and more oxidative PdO species are maintained owing to the intimate interaction between Pd and CeO2-ZrO2. Therefore, improved reduction capability and superior three-way catalytic performance are achieved for the modified Pd/CeO2-ZrO2/Al2O3 catalyst after aging treatment. (C) 2018 Elsevier Ltd. All rights reserved.