A highly efficient Rh-modified Pd/Al2O3 close-coupled catalyst

The close-coupled catalysts Pd/Al2O3 and Rh-Pd/Al2O3 were prepared by the impregnation method and characterized by H-2 temperature-programmed reduction, CO chemisorption, and X-ray photoelectron spectroscopy. Both overall catalytic activity and specific reactions associated with C3H8 elimination were assessed. The light-off temperature and complete conversion temperature decreased by 23 and 18 degrees C, respectively, upon addition of Rh to the Pd/Al2O3 catalyst. The addition of Rh promotes the catalytic activity during C3H8 reactions, particularly in the presence of NO. The introduction of Rh not only inhibits sintering of PdOx and increases the dispersion of these same species, but also changes the electronic state of the PdOx in the catalyst. (C) 2015, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.