Influence of calcination temperature on the structure and catalytic performance of CuOx-CoOy-CeO2 ternary mixed oxide for CO oxidation

Influence of calcination temperature (400−800 °C) on the structure and catalytic activity of CuOx-CoOy-CeO2 ternary mixed oxide (atomic Cu:Co:Ce ratio of 1:5:5) prepared by co-precipitation method is investigated by N2 physisorption, XRD, TPR, TEM, TG-DTA, XPS, and CO oxidation reaction. The as-synthesized CuOx-CoOy-CeO2 undergoes successive structural changes with the calcination temperature, involving the hydroxide dehydration below 400 °C, enhanced interaction between Co3O4 and CeO2 at ca. 600 °C, and Co3O4 decomposition to CoO at 700 °C. The catalyst calcined at 600 °C shows a relative enrichment of Cu+ on the surface of CuOx-CoOy-CeO2 and an enhanced interaction between Co3O4 and CeO2 along with the appearance of oxygen vacancies in CeO2, which seems to be responsible for its highest catalytic activity for CO oxidation among all the tested catalysts. The complete conversion of CO is obtained at 70 °C and about 50% of CO conversion is reached at 55 °C.

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► Mutual interaction between Co3O4 and CeO2 is involved during calcination of the catalyst.
► Oxygen vacancies are beneficial to achieve interaction between Co3O4 and CeO2.
► Enrichment of Cu and Co on the surface of as-prepared catalysts is found.
► Complete CO conversion over CCC600 is obtained at 70 °C and about 10% of CO conversion is reached at 30 °C.