Ceria-Modified Manganese Oxide/Titania Materials for Removal of Elemental and Oxidized Mercury from Flue Gas

摘要

High surface area ceria-titania materials were used as supports for manganese oxide for both warm-gas mercury capture and low temperature selective catalytic reduction. These materials exhibited excellent mercury capture capability at 175 °C. Increasing manganese loadings improves the mercury capacities. In the presence of SO2, only a small decrease in mercury capacity was observed for the CeO2—TiO2 adsorbents. CeO2—TiO2 adsorbents similarly showed excellent stability in the presence of CO and NO. It was also found that the CeO2—TiO2 support can capture Hg and Hg~(2+) simultaneously from nitrogen at 175 °C; the total mercury capacities were high. Brunauer—Emmentt—Teller surface area measurements suggested that increasing manganese loading reduced the surface area due to pore blockage. X-ray diffraction measurements showed that MnOx is in an amorphous state on CeO2—TiO2 materials. X-ray photoelectron spectroscopy (XPS) results indicate that the adsorbed mercury is present as both Hg and Hg~(2+) on these ceria-based materials. The XPS observations also suggest that the incorporation of titanium into the cubic lattice of ceria leads to the formation of more lattice oxygen atoms, leading to greater formation of Hg~(2+) on the CeO2—TiO2 support.