Ce–Fe bimetallic oxide catalysts for CO catalytic oxidation at a high concentration of SO2

Abstract

A series of Ce–Fe bimetallic oxide catalysts were prepared by a hydrothermal method for CO catalytic oxidation at a high concentration of SO₂ in this paper. Ce_0.7Fe_0.3 showed the highest catalytic performance in CO oxidation, reaching higher than 97% CO conversion at above 300 °C in the flue gas containing 1000 ppm CO. When the concentration of SO₂ in the flue gas increased to 1000 mg m⁻³, the CO conversion of Ce_0.7Fe_0.3 remained 86% for 10 hours. The doping of Fe into the CeO₂ lattice resulted in the formation of a CeO₂-like solid solution and the increase in the oxygen vacancy concentration in Ce_0.7Fe_0.3, thus facilitating the CO oxidation activity of Ce_0.7Fe_0.3. In the flue gas containing SO₂, the doping of Fe showed positive effects of resisting the change in crystallinity and mitigating the loss of pore structure. The sulfation of CeO₂ could lead to the formation of Ce₂(SO₄)₃ on the surface, which deactivated the catalyst. The doping of Fe inhibited the reduction of Ce⁴⁺ to Ce³⁺ by SO₂, thereby preventing the formation of Ce₂(SO₄)₃. Furthermore, a small amount of sulfate was deposited on the surface of Ce_0.7Fe_0.3, exhibiting poorer thermal stability than that deposited on CeO₂. The Fe-doping modification played a positive role in enhancing the CO oxidation activity and SO₂-poisoning resistance of Ce_0.7Fe_0.3.