Co(3)O(4)−CeO(2) Nanocomposites for Low‐Temperature CO Oxidation

In an effort to combine the favorable catalytic properties of Co(3)O(4) and CeO(2), nanocomposites with different phase distribution and Co(3)O(4) loading were prepared and employed for CO oxidation. Synthesizing Co(3)O(4)‐modified CeO(2) via three different sol‐gel based routes, each with 10.4 wt % Co(3)O(4) loading, yielded three different nanocomposite morphologies: CeO(2)‐supported Co(3)O(4) 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 Co(3)O(4) surface layer, reducing the light‐off temperature of CeO(2) by about 200 °C. In contrast, intermixed oxides and Co‐doped CeO(2) suffered from lower dispersion and organic residues, respectively. The performance of Co(3)O(4)‐CeO(2) nanocomposites was optimized by varying the Co(3)O(4) loading, characterized by X‐ray diffraction (XRD) and N(2) sorption (BET). The 16–65 wt % Co(3)O(4)−CeO(2) catalysts approached the conversion of 1 wt % Pt/CeO(2), rendering them interesting candidates for low‐temperature CO oxidation.