Pt-Modified Mn–Cu Catalysts for CO Oxidation in the Presence of SO2: Effects of Calcination Temperature and Pt Loading

The control of CO emissions from iron and steel sintering flue gas has received increasing attention. In this work, Pt-loaded Mn–Cu catalysts were prepared by a redox precipitation method to investigate the effects of Pt loading and calcination temperature on low-temperature CO oxidation activity and SO2-induced deactivation behavior. Among the tested catalysts, 1Pt/MnCu-300, containing 1 wt.% Pt and calcined at 300 °C, exhibited the highest low-temperature CO oxidation activity and achieved complete CO conversion at 75 °C. Under the specified SO2-containing test conditions, all catalysts eventually underwent severe and largely irreversible deactivation, whereas Pt loading and calcination temperature altered the transient CO-conversion decay profiles. Pt/MnCu-450 retained high CO conversion for a longer initial period during SO2 exposure than the other catalysts in the calcination-temperature series; however, this observation does not by itself demonstrate superior intrinsic SO2 tolerance because the present experiments did not quantify SO2 breakthrough, sulfur uptake, or active-site-normalized deactivation rates. Characterization results show that Pt modification increased the specific surface area, altered the Mn3+/Mn4+ ratio and surface oxygen species, promoted oxygen-vacancy formation, and enhanced CO adsorption and redox properties. These physicochemical changes are correlated with the improved low-temperature CO oxidation activity of Pt-modified Mn–Cu catalysts. This work clarifies the effects of Pt loading and calcination temperature on CO oxidation performance and on the transient response to SO2 exposure.