Supported Manganese Dioxide Catalyst for Seawater Flue Gas Desulfurization Application

Ceramic-supported manganese dioxide catalyst, MnO2-ceramic, prepared by impregnation- precipitation method and calcined at 350 degree C, was exposed to flue gases to investigate the catalytic oxidation of sulphur dioxide in flue gas at seawater buffering system. The results showed that compared with acid treated ceramic, MnO2-ceramic gained 2%-46% higher Desulfurization efficiency in temperature range of 15-75 degree C. MnO2-ceramic exhibited 57% desulfurization efficiency at its favorable temperature (60 degree C) while ceramic showed 11% Desulfurization efficiency at 60 degree C. MnO2-ceramic was found to catalyze S(W)oxidation even at low pH (pH<4) while the reaction rate of noncatalytic S(IV) oxidation is negligible under the identical conditions. No catalytic activity decay was observed after 40 hours' run. XPS reveals that the Mn was in the oxidation state of +4 for the MnOx-ceramic. SEM-EDS and XRD indicated that the good catalytic activity of MnO2-ceramic at low temperature could be attributed to high dispersion of MnO2 on ceramic support. The high performance of MnO2-ceramic on the SO2 removal appeared to be promising in the seawater flue gas desulfurization industrial application when high sulfur coals were burned.