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 NOx pollutants. The study reveals the synergistic interaction between two activate agents, copper (Cu) and manganese (Mn), on fly ash (FA), achieving impressive NOx 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 NOx 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.