Elemental mercury catalytic oxidation removal and SeO 2 poisoning investigation over RuO 2 modified Ce-Zr complex

摘要

The mercury emission from coal-fired flue gas has drawn lots of attention worldwide. To achieve more efficient catalytic oxidation of Hg0in both high and low temperature, the RuO2modified Ce-Zr solid solution catalysts were prepared and evaluated at various conditions. It was found the polyvinylpyrrolidone (PVP) promoted RuO2/Ce0.6Zr0.4O2catalyst displayed higher significant catalytic activity for Hg0oxidation. The mechanism of Hg0oxidation over RuO2/Ce0.6Zr0.4O2(PVP) was studied through various techniques, and Hg0oxidation approaches were found to consist of two steps: chemisorption process and regeneration process. The adsorbed Hg0was first oxidized with surface chemisorbed oxygen species to form HgO, which could desorb from the surface of catalysts by itself in absence of HCl. Also, the HgO could reacts with Cl?in catalyst or adsorbed HCl to form HgCl2, which could desorb into gas phase more readily. O2is indispensable for the chemisorption process. And the doping RuO2might have a synergistic effect with supporter, which could facilitate chemisorption process. Furthermore, SeO2poisoning of catalyst was investigated for the first time and found the existence of SeO2could slightly inhibit Hg0chemical adsorption process on the surface of the catalyst, while the regeneration process did not significantly affect.