Elemental mercury catalytic oxidation removal and SeO2 poisoning investigation over RuO2 modified Ce-Zr complex

Abstract

The mercury emission from coal-fired flue gas has drawn lots of attention worldwide. To achieve more efficient catalytic oxidation of Hg0 in both high and low temperature, the RuO2 modified Ce-Zr solid solution catalysts were prepared and evaluated at various conditions. It was found the polyvinylpyrrolidone (PVP) promoted RuO2/Ce0.6Zr0.4O2 catalyst displayed higher significant catalytic activity for Hg0 oxidation. The mechanism of Hg0 oxidation over RuO2/Ce0.6Zr0.4O2(PVP) was studied through various techniques, and Hg0 oxidation approaches were found to consist of two steps: chemisorption process and regeneration process. The adsorbed Hg0 was 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. O2 is indispensable for the chemisorption process. And the doping RuO2 might have a synergistic effect with supporter, which could facilitate chemisorption process. Furthermore, SeO2 poisoning of catalyst was investigated for the first time and found the existence of SeO2 could slightly inhibit Hg0 chemical adsorption process on the surface of the catalyst, while the regeneration process did not significantly affect.