Manganese doped CeO2-ZrO2 catalyst for elemental mercury oxidation at low temperature

To develop an efficient catalyst used for elemental mercury (Hg-0) oxidation at low temperature in coal-fired power plant, Mn doped CeO2-ZrO2 catalysts were synthesized and studied concerning their performance on Hg-0 oxidation. Under the atmosphere of simulated coal-fired flue gas, Ce0.47Zr0.23Mn0.3O2 (CZMO.3) exhibited the best activity at 150 degrees C. It was found that Hg-0 oxidation performance over CZMO.3 was determined by the flue gas compositions. Gaseous O-2 was important for the oxidation process, because it regenerated the lattice oxygen and replenished the chemisorbed oxygen, which boosted Hg-0 oxidation. HCl and NO could improve the Hg-0 oxidation efficiency slightly, respectively. In N-2 + HCl + O-2 atmosphere, the Hg-0 oxidation efficiency observed was significantly higher than those in N-2 + O-2 or N-2 + HCl atmosphere. Compared with the effects of HCl on the Hg-0 oxidation activity, the similar results were obtained for effects of NO on the performance Hg-0 oxidation. NO could facilitate the Hg-0 oxidation activity, especially in the presence of O-2. In N-2 + SO2 atmosphere, SO2 inhibited Hg oxidation. In N-2 + O-2 + SO2 atmosphere, SO2 promoted Hg oxidation probably due to the generation of SO3. Water vapor inhibited Hg oxidation, because it diminished the HCl and Hg adsorption. The characterization of the CZM0.3 indicated that the higher activity of the catalyst was most likely attributed to the presence of more oxygen vacancies, enhanced Mn4+/(Mn4+ + Mn3+) ratio and more surface adsorbed oxygen on the catalyst surface. (C) 2016 Elsevier B.V. All rights reserved.