(A) study on the competitive oxidation of CO and $H_2$ over $CeO_2$-based catalysts

Abstract

$CuO_x/CeO_2$ is a promising catalyst for preferential CO oxidation, a method which selectively oxidizes CO in H2-rich fuel. However, there has rarely been systematic investigation for a fundamental understanding of catalytic systems due to the complexity of this process. In addition, an analysis of the catalytic properties of $CeO_2$ itself is very important because the lattice oxygen of $CeO_2$ directly participates in the oxidation reaction. This research intends to elucidate the active site of CO and $H_2$ oxidation over $CuO_x/CeO_2$ systematically by clearly analyzing the role of ceria as a catalyst. For this purpose, the catalytic properties of rare-earth (RE) doped-$CeO_2$ (active support) and $CuO_x/CeO_2$ are investigated with regard to the individual and competitive oxidation of CO and $H_2$. With this strategy, it is found that the RE elements inhibit the oxidation reactivity of $CeO_2$ and that the high CO reactivity is attributed to the $CuO_x-CeO_2$ interface, with the oxidation reactivity of hydrogen very active on the $CeO_2$ surface. This is the first report to analyze the active sites of the $H_2$ oxidation over $CuO_x/CeO_2$, which, despite numerous related studies, has thus far remained ambiguous. The results here represent a more viable approach toward the systematic study of complex catalytic systems.