Synthesis, characterization, and SO2 removal capacity of MnMgAlFe mixed oxides derived from hydrotalcite-like compounds

Fe (III), Mn (II)-substituted Mg–Al hydrotalcite-like compounds were prepared by co-precipitation method and MnMgAlFe mixed oxides derived from hydrotalcite-like compounds (calcination at 1023 K for 4 h) were tested for SO2 removal under the conditions similar to those of FCC units. XRD, IR, TG/DTA and N2 adsorption analysis were performed to investigate the physicochemical and textural properties of the samples. The results showed that all samples exhibited good dispersion of metal oxides in the matrix. The SO2 adsorption–reduction tests showed that on the basis of MgAl adsorbent, addition of a certain amount manganese and iron could enhance the the SO2 removal capacity and adsorption rates of catalysts in FCC units and the sample that contains 5% Fe and 10% Mn showed the best effect. Further analysis suggested that Fe and Mn could cooperatively promote the oxidation of SO2 to SO3 that is easier to be chemisorbed by catalysts and Fe simultaneously played a role as reducing promoter which is essential for reusability of the catalysts.

► MnMgAlFe oxides derived from hydrotalcite-like compounds were prepared.
► These catalysts were tested for SOx removal in FCC flue gas.
► Addition of Fe, Mn could enhance the the SO2 removal capacity and adsorption rate.
► Fe, Mn could cooperatively promote the oxidation of SO2 to SO3.
► Fe is also essential for reusability of the catalysts as a reducing promoter.