Characterization of γ-Al2O3 supported Pd-Cu bimetallic catalysts by EXAFS, AES and kinetic measurements

Pd-Cu/gamma-Al2O3 bimetallic catalysts were prepared according to different impregnation sequences of gamma-Al2O3 and characterized by XRD, EXAFS and AES. The catalysts were tested for the selective hydrogenation of aqueous nitrate solutions to nitrogen. The reaction selectivity was found to be dependent on the catalyst preparation procedures, which affect the spatial distribution of metallic copper and palladium phases. The AES examination shows that in the catalyst exhibiting a higher nitrogen production yield, the very first surface sublayers are enriched with palladium atoms. On the other hand, the EXAFS investigation confirms no significant structural differences among catalyst samples synthesized, which results into identical activity for nitrate removal.