Efficient low-temperature CO removal from high-humidity sintering flue gas by combination Cu and OMS-2

The non-precious metal manganese-based catalysts currently show insufficient CO catalytic oxidation performance in actual sintering flue gas conditions, with increased water vapor levels causing catalyst deactivation. This study utilized a high-performance manganese dioxide octahedral molecular sieve (OMS-2). The effect of metal doping on the catalytic CO oxidation performance was investigated in preparing OMS-2 using the co-precipitation method. The experiments showed that Cu doping increased CO conversion efficiency more than other metals (Co, Ag, Zn, and Fe), with optimal performance achieved at a 1.91 wt% doping level. Besides, Cu doping significantly enhanced water resistance of the catalyst, enabling effective CO removal in high-humidity conditions. The study observed that Cu ions infiltrated the catalyst framework by substituting some of the Mn ions, creating additional active sites in the form of oxygen vacancies and improving surface oxygen mobility, thereby enhancing the performance of CO catalytic oxidation. Furthermore, Cu doping demonstrated selective absorption of water vapor, with Cu_xO in the catalyst, effectively adsorbing water vapor and protecting the initial active sites, thereby mitigating water vapor-induced poisoning. Even in 15 vol% H₂O at 150 °C, 1.91%Cu-OMS-2 maintained total catalytic activity. Therefore, the co-precipitation method-prepared 1.91%Cu-OMS-2 catalyst holds excellent potential for CO removal in sintering flue gas and shows promise for practical applications.