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

The key challenge for controlling Hg-0 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 Hg-0 removal (100%) and NO conversion (99%) are concurrently reached at 180 degrees 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 O-2 were beneficial to Hg-0 oxidation, while NH3 competitive adsorption with Hg-0 and consumption of active oxygen species prevent the Hg-0 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 Hg-0 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 Hg-0 in industry.