Synergistic removal of NO and Hg0 over Co-Mn/TiO2 catalyst: High efficiency and in-depth reaction mechanism

The key challenge for controlling Hg0 using selective catalytic reduction (SCR) technology is to develop a suitable catalyst capable of operating in a cost-effective manner, so it is necessary to study the in-depth reaction mechanism. Herein, Co-Mn/TiO2 catalysts were fabricated by sol-gel method, excellent stability and high efficiency of Hg0 removal (100%) and NO conversion (99%) are concurrently reached at 180 °C, which are benefited from the abundant active oxygen species on the catalysts. In order to clarify the synergistic reaction process, the mechanism of mutual effects between SCR atmosphere and Hg0 is highly dedicated. Specifically, NO and O2 were beneficial to Hg0 oxidation, while NH3 competitive adsorption with Hg0 and consumption of active oxygen species prevent the Hg0 oxidation. Impressively, the inhibition effect of NH3 was not weakened but also intensified, mainly due to the co-existence of NO and NH3 could induce partial HgO reduction. What's more, the direct evidence for the synergistic reaction mechanism of NO and Hg0 is hypothesized by a combination of XPS and in-situ DRIFTs. These findings thus open up a way to address the simultaneous removal of NO and Hg0 in industry.