Abstract There are large amounts of CO pollutants in the off‐gas of the iron and steel industry, which cause serious harm to the environment and human health. To control the emission of CO more effectively, in this paper, LaMn1‐xCuxO3 (x?=?0, 0.25) perovskite catalysts were prepared and then modified by dilute nitric acid. And the physicochemical properties and the catalytic activity of perovskite were investigated and analyzed. The activity results indicate that the Cu2+ substitution and acid treatment could obviously promote the catalytic activity of catalysts for CO oxidation. Among the prepared samples, LaMn0.75Cu0.25O3‐H exhibits the highest activity with 90% CO conversion at 176.5°C, and the self‐sustained combustion of CO is successfully achieved. And the long‐time stability test shows that LaMn0.75Cu0.25O3‐H can keep 100% CO conversion, and the activity remains almost unchanged. Combined with the x‐ray photoelectron spectroscopy (XPS) and H2 temperature‐programmed reduction (H2‐TPR) results, the increased activity of LaMn0.75Cu0.25O3‐H catalyst is mainly ascribed to the high concentration of Mn4+ and abundant oxygen vacancies. On the other hand, the morphology of perovskite catalysts was remolded by acid etching, and the formation of the porous structure significantly increases the specific surface area. The above results show that the substitution of Cu and acid treatment for perovskite catalysts is a feasible strategy to improve CO catalytic combustion activity.
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