Abstract: Pure γ-Al₂O₃and modified alumina (2.5%La2.5%Ba/Al2O3) were calcined at 550 ℃ and 950 ℃,on which Pd and Rh were respectively loaded to form series catalytic materials.By analysis of precious metal dispersity and TPR experiment,the effect of alumina preparation conditions on catalytic activity were studied.Results showed that the precious metal dispersity on 2.5%La2.5%Ba/Al₂O₃ was superior to on pureγ-Al₂O₃,interaction of 2.5%La2.5%Ba/Al₂O₃ with Rh³⁺ was stronger than that of with Pd2+so as to have better dispersity;Pd on the high temperature calcined 2.5%La2.5%Ba/Al₂O₃ had better dispersity and Rh was to the contrary.TPR results showed that precious metals on calcined 2.5%La2.5%Ba/Al₂O₃at 950 ℃ had better lowtemperature reduction activity,and lowtemperature reduction activity of 2.5%La2.5%Ba/Al₂O₃-Pd was higher than that of 2.5%La2.5%Ba/Al₂O₃-Rh.

Key words: Three way catalyst')">

Three way catalyst, rare earth element, Al₂O₃, precious metal