Unraveling the role of bimetal oxide CuO/MnO2 on modified catalyst from solid waste incineration fly ash to enhance NOx removal

Abstract

A novel catalytic system employing a modified fly ash catalyst doped with bimetal oxides has been investigated for its efficacy in selective catalytic reduction (SCR) with ammonia (NH₃) to reduce NO_x pollutants. The study reveals the synergistic interaction between two activate agents, copper (Cu) and manganese (Mn), on fly ash (FA), achieving impressive NO_x removal efficiency. The best-performing catalyst, FA/Cu/Mn-5, is composed of 90 % fly ash, 5 % copper, and 5 % manganese. It removes 98.5 % of NO_x at 200°C. Copper oxide (CuO) helps speed the reaction by converting nitrogen monoxide (NO) into nitrogen dioxide (NO₂), an important part of the SCR process. Manganese oxide (MnO₂), an enhancer of oxygen availability, can promote NH₃ oxidation, effectively lowering the operational temperature and mitigating the formation of nitrous oxide (N₂O). This contrasts with previous research, which reported significant N₂O generation, a major greenhouse gas. Therefore, this current study offers a more sustainable approach to emission control. This study also highlights the critical role of reactive intermediates, such as NO₂, in driving the SCR mechanism, underscoring the potential of modified fly ash catalysts to combat air pollution effectively.