The Effects of Ce Modification for Zr-MnO2 Catalyst in Element Mercury Adsorption and Oxidation

To obtain a higher Hg⁰ removal efficiency, Ce was used as modifier for Zr-MnO2 in Hg⁰ removal process. The experimental results showed that after Ce was added, both the Hg⁰ adsorption efficiency and Hg⁰ oxidation efficiency of the catalysts were improved. Ce0.1-Zr-MnO2 achieved largest Hg⁰ adsorption capacity and highest Hg⁰ oxidation efficiency. Some characterizations were performed to reveal the promotion effects of Ce modification. The results of BET indicated that after Ce modification, the surface area of the catalysts was generally increased, which could lead to more active sites on the catalysts surface for Hg⁰ removal process. The interactions between CeO2, Mn2O3 and ZrO2 would lead to more active amorphous Mn2O3 on the catalysts surface and this was confirmed by XRD results. The H2-TPR results indicated that the Mn species on the Ce modified catalysts surface could be reduced more easily compared with Zr-Mn. The XPS analysis results indicated that the ratio of Mn⁴⁺ / (Mn⁴⁺ + Mn³⁺) and chemisorbed oxygen relative concentration on the catalysts surface will increased with the addition of Ce. Furthermore, the appropriate Ce addition ratio was 0.1 for Zr-Mn catalyst, which could contribute to the appropriate formation of synergy between Ce and Mn and thus lead to the highest Hg⁰ adsorption efficiency and Hg⁰ oxidation efficiency.