Synthesis of inexpensive ternary metal oxides by the co‐precipitation method for catalytic oxidation of carbon monoxide

By using a simple co‐precipitation method, new Fe₂O₃‐based nanocatalysts (samples) were synthesized. The samples were composites of two or three transition metal oxides, MO_x (M=Fe, Mn, Co, Ni, and Cu). The average size of CuO crystallites in the composites composed of two oxide components (CuO−Fe₂O₃) was about 14.3 nm, while in those composed of three (CuO−MnO_x−Fe₂O₃), the composite's phase compositions were almost in the amorphous form when annealing the sample at 300 °C. The latter sample had a specific surface area higher than that of the former, 207.9 and 142.1 g/m², respectively, explaining its higher catalytic CO oxidation. The CO conversion over the CuO−MnO_x−Fe₂O₃‐300 catalyst (1 g of catalyst, 2600 ppm of CO concentration in air, and 1.0 L/min of gas flow rate) begins at about 40 °C; the temperature for 50 % CO conversion (t₅₀) is near 82 °C; and CO removal is almost complete at t₉₉ ≈110 °C. The activity of the optimal sample was tested in different catalytic conditions, thereby observing a high durability of 99–100 % CO conversion at 130 °C. The obtained results were derived from XRD, FTIR, BET, SEM, elemental analysis and mapping, as well as catalytic experiments.