Palladium–vanadium interaction in binary supported catalysts

We have studied the activity and selectivity of Pd/γ-Al₂O₃, VO_x/γ-Al₂O₃ and Pd–VO_x/γ-Al₂O₃ catalysts for the decomposition of NO and the reduction of NO with CO. Pd–VO_x/γ-Al₂O₃ catalysts were prepared by anchoring Pd(AcAc)₂ on VO_x/γ-Al₂O₃. Characterization of the binary samples by hydrogen chemisorption and TPR measurements indicated that the reduction of VO_x is enhanced by a close contact with palladium and that partially reduced vanadia decorate noble metal particles. This palladium–vanadium interaction alters the catalytic properties of palladium: the activity for NO decomposition is higher for the binary sample and, for the NO–CO reaction, both the activity and the selectivity to N₂ increase when vanadium is in contact with palladium.