Effect of the Fe2O3@TiO2 core-shell structure on CO catalytic oxidation and SO2 poisoning resistance

The core-shell Fe2O3@TiO2 and FeTiOx mixed oxide catalysts were prepared to explore the effect of the core-shell structure on the catalytic oxidation of CO under a high concentration of SO2. The core-shell structure helped inhibit the sintering of nanoparticles and enabled Fe2O3@TiO2 to share a larger specific surface area, pore size and more active chemisorbed oxygen species than FeTiOx, promoting the CO catalytic performance. FeTiOx and Fe2O3@TiO2 reached 84% and 96% conversion efficiency in the flue gas containing 1000 ppm CO at 300 degrees C. When SO2 was added to the flue gas, the CO conversion efficiency of FeTiOx dropped to about 10% after 5 h, while Fe2O3@TiO2 still achieved 60% CO conversion efficiency. The TiO2 shell of Fe2O3@TiO2 reacted with SO2 to protect the inner active sites from exposure to SO2, while the FeTiOx surface without shell protection was deposited by ferric sulfate and deactivated. Although the amount of sulfate on Fe2O3@TiO2 was larger than that on FeTiOx, the poor thermal stability of titanic sulfate made it decompose more easily than ferric sulfate. Therefore, the core-shell structure showed a critical role in promoting the resistance to SO2-poisoning of Fe2O3@TiO2 in CO catalytic oxidation.