Promotion of a Pd/Al2O3 close-coupled catalyst by Ni

The influence of a nickel promoter on the catalytic behavior of a modified alumina supported Pd close-coupled catalyst was investigated. Doping with nickel improved the catalytic activity for the reactions of C3H8, especially over the aged catalyst. T-50 and T-90 of the aged Pd catalyst were decreased by 31 and 30 degrees C, respectively. The single reaction results revealed that doping with Ni promoted the catalytic activity for the C3H8 + NO reaction. The fresh and aged catalysts were characterized by H-2-temperature-programmed reduction, CO chemisorption, high resolution transmission electron microscopy, and X-ray photoelectron spectroscopy, which revealed that the doping with Ni inhibited the sintering of active PdOx species and the formation of undesired metallic Pd-0, and led to improved reducibility of active PdOx and increased the surface area of PdOx species. (C) 2015, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.