Effects of Au–Ce strong interactions on catalytic activity of Au/CeO2/3DOM Al2O3 catalyst for soot combustion under loose contact conditions

Abstract

Au/3DOM (three-dimensionally ordered macroporous) Al2O3 and Au/CeO2/3DOM Al2O3 were prepared using a reduction-deposition method and characterized using scanning electron microscopy, N2 adsorption-desorption, X-ray diffraction, transmission electron microscopy, ultraviolet-visible spectroscopy, temperature-programmed hydrogen reduction, and X-ray photoelectron spectroscopy. Au nanoparticles of similar sizes were well dispersed and supported on the inner walls of uniform macropores. The norminal Au loading is 2%. Al–Ce–O solid solution in CeO2/3DOM Al2O3 catalysts can be formed due to the incorporation of Al3+ ions into the ceria lattice, which causes the creation of extrinsic oxygen vacancies. The extrinsic oxygen vacancies improved the oxygen-transport properties. The strong metal–support interactions between Au and CeO2 increased the amount of active oxygen on the Au nanoparticle surfaces, and this promoted soot oxidation. The activities of the Au-based catalysts were higher than those of the supports (Al2O3 or CeO2/3DOM Al2O3) at low temperature. Au/CeO2/3DOM Al2O3 had the highest catalytic activity for soot combustion, with T10, T50, and T90 values of 273, 364, and 412 °C, respectively.