Catalytic Reduction of SO2 with CO Over Fe/TiO2 Catalysts: Effect of Pre-sulfurization and Plasma

Sulfur dioxide (SO 2 ) emissions, a major source of air pollution, can be effectively mitigated through catalytic reduction to elemental sulfur using carbon monoxide (CO). In this study, Fe loaded TiO 2 catalysts were synthesized and subsequently subjected to pre-sulfurization treatment under varied conditions. Their catalytic performance was evaluated in SO 2 reduction for thermal and dielectric barrier discharge (DBD) plasma enhanced thermal catalysis. The results showed that OFS-Fe/TiO 2 catalyst with oxygen-free sulfurization (OFS) treatment exhibited the highest catalytic activity, achieving above 90% SO 2 conversion between 250 and 550 °C under oxygen-assisted reaction (OAR), along with long-term stability under 40–60% water vapor. However, the SO 2 conversion were below 20% for Fe/TiO 2 and oxygen-assisted sulfurization OAS-Fe/TiO 2 catalysts within 250 to 400 °C. Notably, the significantly enhanced catalytic performance of the OFS-Fe/TiO 2 catalyst was probably attributed to the high dispersion of Fe over nano-TiO 2 , the lower Fe 2+ /Fe 3+ ratio, and the formation of active FeS 2 species detected by SEM-EDS, XPS and TPD techniques. Furethermore, a conversion efficiency exceeding 90% was maintained throughout 80 to 550 °C under DBD plasma reaction over POFS-Fe/TiO 2 catalyst with room-temperature DBD plasma oxygen-free sulfurization treatment, surpassing thermal catalysis performance. The significantly enhanced low-temperature activity of plasma catalysis was attributed to the lowest Fe 2+ /Fe 3+ ratio, together with the transformation of FeS 2 into FeS, generating more sulfur vacancies. In-situ DRIFTS experiments confirmed two distinct SO 2 adsorption and reduction mechanisms between Fe/TiO 2 and OFS-Fe/TiO 2 catalysts. The results demonstrate that pre-sulfurization and plasma modification serve as an effective catalytic strategy to enhance CO-mediated SO 2 reduction, offering a sustainable emission control approach through sulfur resource utilization. Graphical