Co3O4-CeO2 Nanocomposites for Low-Temperature CO Oxidation

In an effort to combine the favorable catalytic properties of Co3O4 and CeO2, nanocomposites with different phase distribution and Co3O4 loading were prepared and employed for CO oxidation. Synthesizing Co3O4-modified CeO2 via three different sol-gel based routes, each with 10.4 wt % Co3O4 loading, yielded three different nanocomposite morphologies: CeO2-supported Co3O4 layers, intermixed oxides, and homogeneously dispersed Co. The reactivity of the resulting surface oxygen species towards CO were examined by temperature programmed reduction (CO-TPR) and flow reactor kinetic tests. The first morphology exhibited the best performance due to its active Co3O4 surface layer, reducing the light-off temperature of CeO2 by about 200 degrees C. In contrast, intermixed oxides and Co-doped CeO2 suffered from lower dispersion and organic residues, respectively. The performance of Co3O4-CeO2 nanocomposites was optimized by varying the Co3O4 loading, characterized by X-ray diffraction (XRD) and N-2 sorption (BET). The 16-65 wt % Co3O4-CeO2 catalysts approached the conversion of 1 wt % Pt/CeO2, rendering them interesting candidates for low-temperature CO oxidation.