Preparation of CeO2-ZrO2-Al2O3 with a composite precipitant and its supported Pd-only three-way catalyst

Acomposite precipitant composed of ammonia and ammoniumcarbonate was used to prepare CeO2- ZrO2-Al2O3 (CZA). For comparison, two other CZA samples were prepared using ammonia and ammonium carbonate as the precipitants, respectively. Differences in the textural, structural and redox properties, together with the evolution upon thermal aging treatment and the catalytic performance of the corresponding Pd-only three-way catalysts, were investigated systematically. The choice of precipitant was found to affect the interactions between CeO2-ZrO2 (CZ) and Al2O3. When ammonia was used as the precipitant, the resulting CZ and Al2O3 seemed insusceptible to each other, thus the obtained CZA composite displayed inferior thermal stability due to the weakest interaction between CZ and Al2O3. In the case of ammonium carbonate, stronger interaction between CZ and Al2O3 enhanced the thermal stability of CZA, but in the meantime, the homogeneity of the CZ solid solution was severely impaired by Al2O3, leading to undesirable redox performance. Fortunately, the use of the composite precipitant brought about favorable interaction between CZ and Al2O3, leading to excellent textural and structural properties along with the highest thermal stability of the CZA compound. Consequently, the corresponding Pd-based catalyst displayed prominent reducibility and oxygen storage capacity (OSC) performance, as well as superior three-way catalytic performance.

Duke Scholars

Author Li Lan Molecular Genetics and Microbiology