Highly efficient removal of CO from sintering flue gas over a Pd-modified catalyst

Abstract To address the demand for efficient CO removal from steel-sintering flue gas, we developed a Cu–Ce–Fe/TiO 2 composite catalyst modified with 1 wt% Pd, using an ultrasound-assisted impregnation method. Evaluation of the catalytic performance revealed that the introduction of Pd significantly enhanced the low-temperature activity of the catalyst. Specifically, the temperature required for 99 % CO conversion (T 99 ) decreased from 230 °C to 170 °C after Pd modification. Furthermore, the catalyst demonstrated excellent stability and resistance to poisoning, maintaining a CO conversion rate of over 85 % in a complex flue gas stream containing 20 ppm of SO 2 and 12 % H 2 O. Mechanistic investigations indicated that the performance enhancement is attributable to several factors. Palladium inhibits the agglomeration of the active components, narrowing the particle size distribution to a more uniform 0–15 nm range. H 2 -TPR analysis confirmed improved low-temperature reducibility, with the main reduction peak shifting from 123 to 93 °C. Furthermore, XPS analysis showed that Pd modulates the interfacial electronic structure, which promotes the partial reduction of Cu 2+ to lower valence states and optimizes the ratio of the Ce 3+ /Ce 4+ redox couple. Consequently, synergistic active sites are formed among the multiple metallic elements, which markedly improves low-temperature redox performance and increases the concentration of surface oxygen vacancies. This research confirms that the Pd modification strategy is highly effective in improving the overall performance of the catalyst. It presents a cost-effective solution for the advanced purification of flue gas in the steel industry, offering a combination of high low-temperature activity, robust stability, and strong resistance to common catalytic poisons.