The effect of rare earth modification on ceria–zirconia solid solution and its application in Pd-only three-way catalyst

Abstract

The influence of rare earth elements (La, Nd, Pr, Sm and Y) addition to Ce 0.2Zr 0.8O 2 and its supported Pd-only three-way catalysts has been investigated by X-ray diffraction (XRD), N 2 adsorption/desorption, X-ray photoelectron spectroscopy (XPS) and H 2 temperature programmed reduction (H 2-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.