Abstract: A series of modified alumina with different mass fractions (5%, 10%,20%,and 30%) of La/Ba were prepared by γ-Al₂O_3.All samples were calcined at 550,950,1 050，and 1 200 ℃ respectively.Pore structure of all samples were characterized by BET,pore volume, pore diameter,and XRD before and after aging.Influence of La/Ba doping contents on pore structure of modified Al₂O₃ was studied.Results of BET and XRD demonstrated that La/Ba can form large amount of aluminate structure to inhibit γ-Al₂O₃ phase tranfer at high temperature and is good for maintaining stability for both phase structure and pore structure of γ-Al₂O₃.Meanwhile,higher La/Ba content can decreased the surface area,pore volume,and pore diameter,and is not good for precious metals dispersing,especially at 1 200 ℃.Comprehensively considering pore structure and loss rate,2.5%La2.5%Ba/Al₂O₃ has the optimal surface activity and pore structure stability. 

Key words: three-way catalyst, alumina, alkali metals, catalyst activity