Series of bimetallic catalysts Pd-Fe/Al_2O_3 with various palladiumand iron contents were prepared by impregnating metal precursors in differentsequences.Techniques were employed to characterize the catalysts,XRD forthe existing form of the supported metals,XPS for the surface metal contentsand chemical states,in silu IR with the aid of CO as a probe molecule for theinfluence of iron amount and adding sequence upon the dispersion and the elec-tronic state of palladium.On the catalyst prepared by coimpregnating,the pal-ladium and iron contents are higher than those prepared by impregnating in dif-ferent sequence,but the ratio of Pd/Fe(in atom)is lower than those on thelatter two.The iron atoms shield the palladium and enhance the dispersity ofpalladium.In the catalyst prepared by first impregnating with iron and thenwith palladium,the iron has a strong ability to disperse palladium and the dis-persity increases with the iron loading.In the catalyst prepared by first dopingwith palladium and then iron,the Series of bimetallic catalysts Pd-Fe / Al 2 O 3 with various palladiumand iron contents were prepared by impregnating metal precursors in different sequences. Techniques were employed to characterize the catalysts, XRD forthe existing form of the supported metals, XPS for the surface metal contents and chemical states, in silu IR with the aid of CO as a probe molecule for the fluid of iron amount and adding sequence upon the dispersion and the elec-tronic state of palladium. On the catalyst prepared by coimpregnating, the pal-ladium and iron contents are higher than those prepared by impregnating in dif-ferent sequence, but the ratio of Pd / Fe (in atom) is lower than those on thelatter two.The iron atoms shield the palladium and enhance the dispersity ofpalladium.In the catalyst prepared by first impregnating with iron and thenwith palladium, the iron has a strong ability to disperse palladium and the dis-persistence increases with the iron loading. In the catalyst prepared by first doping with palladium and then iron, the