Oxygen buffering capacity of Pr/Tb doped CeO2-ZrO2 mixed oxides

The three-way catalysts (TWCs) promoters Ce0.6Zr0.4O2, Ce0.6Zr0.35Pr0.50O2-y and Ce0.6Zr0.4-xTbxO2-y (x=0.05, 0.10, 0.15) were prepared by sol-gel method, and the catalytic performance was measured for the fully formulated Pt, Rh and Pd TWCs (high ratio of Pd) containing this kind of promoters as the oxygen storage materials of washcoat. The results show that the introduction of Pr and Tb ions into ceria-zirconia solid solution can decrease the ligh-off temperature of fresh TWCs. C3H6 conversion was used as a probe to test the oxygen buffering capacity of washcoat. The washcoats play a role of oxygen storage and the TWCs containing ceria-based oxygen storage materials have higher conversion rate for C3H6 oxidation under the oxygen-deficient condition. Parameter K was put forward through theoretical analysis and test, which offers a method to characterize the oxygen buffering capacity of oxygen storage materials. This method is simple and feasible, and the parameter K coincides with the results of catalytic activity test.