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Abstract: In this paper, five types of ceria–zirconia modified alumina (CZA) were prepared by co-precipitation with supercritical drying (CPS), co-precipitation with common drying (CPC), sol–gel (SG), micro-emulsion (ME) and impregnation (IM) methods, respectively. The corresponding supported Pd-only three-way catalysts (TWC) were also prepared and evaluated in the simulative gasoline engine exhaust. The influence of different preparation methods on the physicochemical properties of CZA mixed oxide and its supported TWC was characterized by X-ray diffraction (XRD), N2 adsorption/desorption and transmission electron microscopy (TEM) techniques. The redox behavior was investigated with H2 temperature-programmed reduction (H2-TPR) experiments. The results reveal that the CZA mixed oxides derived from CPS and ME methods exhibit the relatively higher textural and structural properties as well as better redox behavior, which lead to the better catalytic activity and wider air-to-fuel operation window of the corresponding Pd-only three-way catalysts. [Copyright &y& Elsevier]

Abstract: The influence of rare earth elements (La, Nd, Pr, Sm and Y) addition to Ce0.2Zr0.8O2 and its supported Pd-only three-way catalysts has been investigated by X-ray diffraction (XRD), N2 adsorption/desorption, X-ray photoelectron spectroscopy (XPS) and H2 temperature programmed reduction (H2-TPR) techniques, and that the dynamic oxygen storage capacity (DOSC) has also been evaluated under transient conditions. Special attention was given to the information of structural modification and the effect of doping on the three-way catalytic performance. The phase for all the ceria–zirconia-rare earth ternary solid solution is single tetragonal, irrespective of the treatment temperature applied. The presence of La, Nd and Pr results in enhanced thermal stability, improved reducibility and increased strong metal–support interaction, leading to the relatively higher three-way catalytic activity for all the target pollutants over the corresponding catalysts. The air/fuel operation window is also enlarged due to the increased dynamic oxygen storage capacity. [Copyright &y& Elsevier]

Abstract: The promotional effect of cobalt oxide on the catalytic performance and the physicochemical properties of Pd only three-way catalysts and Ce0.67Zr0.33O2 mixed oxides (CZ) prepared by co-precipitation and impregnation methods have been investigated. It is worthwhile to note that the role of Co significantly depends on the method of Co doping in the CZ. The introduction of cobalt oxide by co-precipitation exhibits significant influence on the catalytic activity of Pd only three-way catalyst with enhancing textural and structural properties, compared to the introduction of cobalt oxide by impregnation method. Furthermore, CZ doped with cobalt oxide by co-precipitation results in the formation of more homogeneous ternary solid solution, which promotes the metal–support interaction between CZ and cobalt metal and improves oxygen storage capacity (OSC) of samples. It also proves that the textural and structural properties of supports can affect the reducibility and oxygen storage capacity of samples at low temperature. [Copyright &y& Elsevier]