Abstract: The promoters Ce_0.6Zr_0.4-xTb_xO_2-y of three-way catalysts (TWCs) were prepared by coprecipitation and sol-gel methods.The XRD and Raman spectra confirm that the Ce_0.6Zr_0.4-xTb_xO_2-y cubic solid solution is formed,and the XPS analysis indicates that the valences of Ce and Tb are maily in the forms of Ce⁴⁺ and Tb³⁺ on the surface of samples.The particle size distribution and TEM show that the solid solution particles are in the form of agglomerate in the liquid.The catalytic performance was also measured for the fully formulated Pt,Rh and Pd TWCs (high ratio of Pd) containing this kind of promoters.The results indicate that the introduction of Tb ions into CeO₂-ZrO₂ solid solution lowers the ligh-off temperature of fresh TWCs.Among TWCs containing the promoters which prepared via coprecipitation method,the sample containing 15% Tb exhibits the lowest ligh-off temperature,that is,18℃,21℃ and 27℃ for CO,C₃H₆ and NO_x conversion,while for those containing the promoters prepared by sol-gel method,the ligh-off temperature does not depend on Tb content,the sol-gel method is better than the coprecipitation method.For the aged samples which have been calcined at 900℃ for 2 h,the optimum Tb content is 5%.