Catalytic oxidation of sulfur dioxide over α-Fe2O3/SiO2 catalyst promoted with Co and Ce oxides
Hematite (α-Fe 2 O 3 ) is a promising alternative to the catalysts currently used due to its low cost, fairly good activity and environmentally friendly properties. In this study, α-Fe 2 O 3 /SiO 2 nanocatalysts promoted with cobalt and cerium (Co 3 O 4 -CeO 2 -α-Fe 2 O 3 /SiO 2 ) were prepared via wet co-impregnation method, and the effects of promoters on catalytic performances for SO 2 oxidation at different temperatures, SO 2 concentrations, cycle numbers, catalytic stability as well as catalyst charging were investigated. The results indicated that SO 2 conversion rose with the increasing of catalyst charging and SO 2 concentration. Also, the as-prepared catalyst had the maximum SO 2 conversion at the reaction temperature of 500 °C, excellent catalytic recyclability and activity stability. Its physicochemical and redox properties were characterized by XRD, BET, SEM, FT-IR and XPS. The results of XRD and FT-IR spectra confirmed that the formation of Ce 2 FeO 4 network in the Co-Ce co-doped catalysts proved the promoting effect of cerium on higher valence state of the active ingredient. The N2 adsorption/desorption results evidenced that cerium could increase the proportion of mesoporous, and the XPS spectra indicated that cobalt and cerium in the catalysts could increase the available oxygen (O β /O α ) for the redox reaction. Due to its excellent low onset temperature, fairly good activity and environmentally friendly properties, the as-prepared catalyst of Co 3 O 4 -CeO 2 -α-Fe 2 O 3 /SiO 2 appeared to be more efficient for the SO 2 conversion in a large concentration range.
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