Mechanistic investigation on the Hg 0 elimination ability of MnO x –CeO x nanorod adsorbents: effects of Mn/Ce molar ratio

Mercury pollution is created by coal combustion processes in multi-component systems. Adsorbent injection was identified as a potential strategy for capturing Hg 0 from waste gases, with adsorbents serving as the primary component. The hydrothermal approach was used to synthesize a series of MnO x –CeO x nanorod adsorbents with varying Mn/Ce molar ratios to maximize the Hg 0 capture capabilities. Virgin CeO x had weak Hg 0 elimination activity; <8% Hg 0 removal efficiency was obtained from 150 °C to 250 °C. With the addition of MnO x , the amount of surface acid sites and the relative concentration of Mn 4+ increased. This ensured the sufficient adsorption and oxidation of Hg 0 while overcoming the limitations of restricted adsorbate-adsorbent interactions caused by the lower surface area, endowing MnO x –CeO x with increased Hg 0 removal capacity. When the molar ratio of Mn/Ce reached 6/4, the adsorbent’s Hg 0 removal efficiency remained over 92% at 150 °C and 200 °C. As the molar ratio of Mn/Ce grew, the adsorbent’s Hg 0 elimination capacity declined due to decreased surface area, weakened acidity, and decreased activity of Mn 4+ ; <75% Hg 0 removal efficiency was reached between 150 °C and 250 °C for virgin MnO x . Throughout the overall Hg 0 elimination reactions, Mn 4+ and O α were in charge of oxidizing Hg 0 to HgO, with Ce 4+ acting as a promoter to aid in the regeneration of Mn 4+ . Because of its limited adaptability to flue gas components, further optimization of the MnO x –CeO x nanorod adsorbent is required. Graphical abstract