Catalytic oxidation of NH3/Hg0 by Cu-TiO2@CeO2 catalyst
In order to mitigate the release of escaping ammonia and gaseous elemental mercury in the SCR system,a series of Cu-TiO2@CeO2 catalysts with mercury and ammoxidation activities were synthesized using the template method.The ammoxidation and mercury oxidation properties were evaluated at 150-400 ℃,and the catalysts were characterized by XRD,BET and XPS.The results indicate that high temperature can enhance the oxidation of NH3 but is not favorable for maintaining high N2 selectivity and Hg0 oxidation performance.With the increase of the mass fractions of Cu and Ce,the activities of ammonia oxidation and mercury oxidation of the catalyst gradually increase,but the selectivity of N2 decreases.Among them,Cu-TiO2@CeO2-5 catalyst with 5％mass fractions of Cu and Ce can achieve ideal removal of NH3 and Hg0.At 350 ℃,the oxidation efficiencies of NH3 and Hg0 are both above 90％,the N2 selectivity is above 95％,and the by-product N2O formation is below 5 × 10-6.The characterization results show that Cu++Ce4+⇌Cu2++Ce3+redox double electric pair forms in the catalyst.The oxides of Cu and Ce act synergically in the oxidation reaction of NH3 and Hg0.A large amount of Oβ participate in the reaction as active oxygen species,effectively promoting the catalytic removal of NH3 and Hg0 concentrations.
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