Rare Earth Doping Effects on Properties of Ceria-Zirconia Solid Solution

摘要

Ce_(0.6)Zr_(0.3)RE_(0.1)O_2(RE = Y, La, Pr, Tb)solid solutions were prepared by co-precipitation technique and characterized by a series of methods. XRD and FT-Raman results show that Ce_(0.6)Zr_(0.3)RE_(0.1)O_2 has cubic fluorite structure. The different dopant ion radii bring different effect on the cell parameter of Ce_(0.6)Zr_(0.3)RE_(0.1)O_2. The X-ray photoelectron spec-troscopy (XPS) results show that the binding energy of Ce3d, Zr3d and O1s for Ce_(0.6)Zr_(0.3)RE_(0.1)O_2 rises compared with that for Ce_(0.6)Zr_(0.4)O_2, indicating that dopant elements change chemistry environment of solid solutions which is available to improve redox performance. Compared with Pd/Ce_(0.6)Zr_(0.4)O_2, doping Y and La does not change air/fuel (A/F) characteristic of TWCs, but doping Pr and Tb widens A/F operating window and makes HC, CO and NO have higher conversion. The light-off temperature of Pd/Ce_(0.6)Zr_(0.3)La_(0.1)O_2 is corresponding to that of Pd/Ce_(0.6)Zr_(0.4)O_2. However, the light-off temperatures of Pd/Ce_(0.6)Zr_(0.3)M_(0.1)O_2(M = Y, Pr, Tb) are lower than that of Pd/C_(0.6)Zr_(0.4)O_2, which keep much lower after high temperature treatments. Among Pd/Ce_(0.6)Zr_(0.3)RE_(0.1)O_2, Pd/Ce_(0.6)Zr_(0.3)Tb_(0.1)O_2 represents wider A/F operating window, higher conversion, lower light-off temperature and better high-temperature resistance.