Synthesis and characterization of pure and (Ce, Zr, Ag) doped mesoporous CuO-Fe₂O₃ as highly efficient and stable nanocatalysts for CO oxidation at low temperature

Highlights: • Highly active and stable Fe-Cu mixed oxides were prepared by co-precipitation method. • Addition of CuO to Fe₂O₃ increases the chemisorbed oxygen, the conductivity and S_BET. • Activation energy of CO oxidation significantly decreased via doping with foreign ions. - Abstract: A series of single and mixed oxide nanocatalysts of mesoporous CuO-Fe₂O₃ with different CuO contents (1–50 wt.%) were prepared by a co-precipitation method and further promoted by trace amounts of CeO₂, ZrO₂ and Ag₂O (0.1–0.5 wt.%) dopants. The original and calcined catalysts were characterized by TG, DTA, XRD, TEM, VSM, N₂ sorption analysis, surface chemisorbed oxygen and DC electrical conductivity measurements. The catalytic performance of these nanocatalysts toward CO oxidation was studied using a conventional fixed bed flow type reactor. The results revealed that the addition of 1–20 wt.% CuO to Fe₂O₃ monotonically increases the specific surface area, the amount of surface chemisorbed oxygen, electrical conductivity and catalytic activity of the nanocatalysts. In addition, the catalytic activity indicated that Fe-Cu mixed oxide nanocatalyst promoted with the three dopants (CeO₂, ZrO₂ and Ag₂O) exhibited the highest catalytic activity with a total conversion of CO into CO₂ at 100 °C. Moreover, the activation energy of CO oxidation decreased from 38.4 to 23.1 kJmol⁻¹ upon treating the catalyst containing 20 wt.% CuO with the three dopants. Finally the effects of various operational parameters were also studied.