Shape effect of ceria in Cu/ceria catalysts for preferential CO oxidation

Abstract

Copper was deposited on different shapes of ceria supports (i.e., rods, cubes, and octahedra) and used as catalysts for preferential CO oxidation in excess amounts of hydrogen. When the same amount of copper was deposited, the copper content on the surface measured by X-ray photoelectron spectroscopy differed significantly, with more copper on the ceria octahedra. Copper seemed to migrate into the bulk ceria to a greater degree on the rods. The Cu/ceria-octahedra showed the highest activity of 95% at 140 degrees C among the three shapes, whereas the Cu/ceria-rods showed higher CO conversion than the Cuiceria-octahedra at higher temperatures. The Cu/ceria-octahedra showed no activity degradation for CO conversion at 140 C over 100 h, whereas the activity decreased by 13% for Cu/ceria-rod and 32% for Cu/ceria-cube at the same temperature. The metals Au and Pt were also deposited on the different shapes of ceria, and their activity and selectivity were evaluated. (C) 2010 Elsevier B.V. All rights reserved.