The Unique CO Activation Effects for Boosting NH3 Selective Catalytic Oxidation over CuOx–CeO2

Slip NH 3 is a priority pollutant of concern to be removed in various flue gases with NO x and CO after denitrification using NH 3 -SCR or NH 3 -SNCR, and the simultaneous catalytic removal of NH 3 and CO has become one of the new topics in the deep treatment of such flue gases. Synergistic catalytic oxidation of CO and NH 3 appears to be a promising method but still has many challenges. Due to the competition for active oxidizing species, CO was supposed to hinder the NH 3 selective catalytic oxidation (NH 3 -SCO). However, it is first found that CO could significantly promote NH 3 -SCO over the CuO x –CeO 2 catalyst. The NH 3 conversion rates increased linearly with CO concentrations in the range of 180–300 °C. Specifically, it accelerated by 2.8 times with 10,000 ppm CO inflow at 220 °C. Mechanism studies found that the Cu–O–Ce solid solution was more active for CO oxidation, while the CuO x species facilitated the NH 3 dehydrogenation and mitigated the competition of NH 3 and CO, further stabilizing the promotion effects. Gaseous CO boosted the generation of active isolated oxygen atoms (O i ) by actuating the Cu + /Cu 2+ redox cycle. The enriched O i facilitated oxidation of NH 3 to NO and was conducive to the NH 3 -SCO via the i-SCR approach. This study tapped the potential of CO for promoting simultaneous catalytic oxidation of coexisting pollutants in the flue gas.