Promoter of （Ce-Zr）02 Solid Solution Modified by Praseodymia in Three-Way Catalysts

The three-way catalysts (TWCs) promoters (Ce-Zr)O2, (Pr-Ce-Zr)O2 and (Pr-Zr)O2 were prepared by solgel like method. They were characterized by XRD, EXAFS and BET surface area determination. The reduction features of the promoters were measured by temperature-programmed reduction (TPR) of He to access the potential for the promoters containing praseodymia as oxygen storage component in three-way catalyst. The (Pr-Zr)O2 cubic solid solution is formed at high temperature up to 800 ℃, which makes it more reducible than the (Ce-Zr)O2 solid solution. For the (Pr-Ce-Zr)O2 samples, the ternary solid solution plays an important role in the reduction process. The performance of the three-way catalysts with fully formulated Pt, Pd and Rh is proceeded by using both light-off temperature under a stoichiometric gas composition and the conversion of CO, C3H6 and NO under changing air/fuel ratio at a constant reaction temperature 400℃. The results indicate that a small amount of praseodymia doping into (Ce-Zr)O2 favors the light-off temperature of C3H6 and NO, and all the catalysts containing praseodymia obviously exhibits enhanced width of S value for NO conversion at lean region (S≥1.00).