Enhanced low-temperature CO oxidation over CuO-Co3O4 catalysts promoted with transition metal oxides

• Synthesis of transition metal oxide (TMO) promoted CuO-Co 3 O 4 catalysts for CO oxidation. • Demonstrating the TMO incorporation effect on structure–property-activity relationship. • CuO-Co 3 O 4 catalysts promoted with CeO 2 and ZrO 2 exhibit superior activity and stability. • Strengthened interactions between TMO and CuO-Co 3 O 4 accounts for excellent performance. Developing highly efficient and robust catalysts for low-temperature CO oxidation is essential for CO abatement in sintering flue gas. CuO-Co 3 O 4 catalysts incorporated with transition metal oxides (TMOs) of CeO 2 , ZrO 2 , NiO or Fe 2 O 3 were synthesized using the sol–gel method. The crystalline structure, morphology, electronic structure, surface active sites and redox properties of the composite catalysts were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), CO temperature-programmed desorption (CO-TPD), H 2 temperature-programmed reduction (H 2 -TPR), and O 2 temperature-programmed oxidation (O 2 -TPO). The influence of incorporating TMO on CO oxidation performance of the composite catalysts was thoroughly investigated. Results indicated that incorporating CeO 2 and ZrO 2 enhanced the CO oxidation activity of CuO-Co 3 O 4 significantly, achieving notably low T 100 temperatures of 134 °C and 150°C. The desired CuO-Co 3 O 4 -CeO 2 and CuO-Co 3 O 4 -ZrO 2 composite catalysts also showed outstanding CO oxidation kinetics performance with low activation energies of 25.36 and 26.41 kJ/mol, and remarkable time-on-stream stability, sustaining a near 100 % CO conversion rate for up to 25 h. The superior CO oxidation performance was associated with the smaller crystallite sizes, uniformly dispersed active sites, abundant oxygen vacancies, and enhanced redox properties, all of which stemmed from the strengthened interfacial interactions among the metal oxides upon CeO 2 and ZrO 2 incorporation. These findings offer valuable insights into the structure–property-activity relationships of the CuO-Co 3 O 4 -TMO composite catalysts, positioning the CuO-Co 3 O 4 -CeO 2 and CuO-Co 3 O 4 -ZrO 2 samples as promising candidates for low-temperature CO oxidation in sintering flue gas treatment.