| Summary: | The effect of the Co-Cu oxide catalysts composition on their physicochemical properties and performance in the deep oxidation of ethanol was studied. The catalysts with Co:Cu molar ratios of 4:1, 1:1, and 1:4 were obtained by calcination (4 h at 500 °C in air) of the coprecipitated precursors and characterized in detail using powder XRD, Raman spectroscopy, N<sub>2</sub> physisorption, H<sub>2</sub>-TPR, and XPS. The powder XRD and Raman spectroscopy indicated the formation of Co<sub>3</sub>O<sub>4</sub> and CuO mixtures rather than Co-Cu mixed oxides. The CuO promoted the Co<sub>3</sub>O<sub>4</sub> reduction; the Co-Cu catalysts were reduced more easily than the single-component Co and Cu oxides and the main reduction maxima were shifted to lower temperatures with increasing cobalt content in the catalysts. The Co-Cu oxide catalyst with a Co:Cu molar ratio of 4:1 exhibited the best performance in ethanol gas-phase oxidation, showing the lowest <i>T<sub>50</sub></i> (91 °C) and <i>T<sub>90</sub>(CO<sub>2</sub>)</i> (159 °C) temperatures needed for 50% ethanol conversion and 90% conversion to CO<sub>2</sub>, respectively. The excellent catalytic properties of this Co-Cu oxide catalyst were ascribed to the synergistic effect of Co and Cu components. The high activity and selectivity of the Co-Cu catalyst was attributed to the presence of finely dispersed CuO particles on the surface of Co<sub>3</sub>O<sub>4</sub>.
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