PREPARATION AND CHARACTERIZATION OF BIMETALLIC Pd-Fe/Al2O3 CATALYSTS—CHARACTERIZATION BY TEM,EDX,XPS and ESR

Suppurted bimetallic catalysts Pd-Fe/AlOwere prepared by im-pregnating method in different dipping sequences.Transmission electron mi-croscopy（TEM-EDX）,X-ray diffraction（XRD）,X-ray photoelectron spec-troscopy（XPS）and electron spin resonance（ESR）were employed to charac-terize the catalysts.It is shown that the impregnating sequence has influence onthe diffusiun and distribution of the metals in the pores of AlOsupport.Themetal group diffusion is controlled by its charge.On the surface of the cata-lysts,the iron is in oxidative state while the palladium is zerovalent whenFeClis first loaded.However,on the surface of the other two,the palladiumis in both oxidated and metallic states.The amount of Fein the catalyst dif-fers with the dipping sequence.ESR results shows that in different catalystsprepared in various sequences Feexists in different environments.