The Catalytic Activity of Manganese-Copper Supported on Coconut Shell–Carbon Activated by Nitric Acid for Low-Temperature NH3-SCR

Coconut shell–activated carbon is a highly promising catalytic carrier due to its chemical stability and high porosity. Meanwhile, manganese-based oxidants are very effective catalysts in NH3-SCR, but their instability restricts their use. In an attempt to create catalysts that perform well at low temperatures, this study characterized nitric acid-modified coconut shell-activated carbon carriers at different concentrations using N2 adsorption-desorption, XRD, BET, XPS, DRIFTS, and other methods. By doping with Cu and Mn as the main active substance, optimal Mn-Cu composite catalysts were prepared. The study found that Mn7Cu3/AC-B catalyst had the best activity at low temperatures, achieving up to 99% denitrification efficiency at 225 °C. The catalyst had the highest content of Mn4+, Cu2+, and Oα, which favored the reaction and made the catalyst more resistant to water and sulfur. The use of the appropriate concentration of nitric acid helps to remove carrier impurities and improve carrier structural parameters, thus enabling uniform dispersion of active substances and facilitating the reaction. Moreover, copper and manganese have a synergistic effect, and the composite catalysts have higher redox capacity, catalyst acidic sites, and N2 selection compared to single manganese catalysts. This study aims to prepare better resistant catalysts for low-temperature reactions and contribute to the optimization of manganese-based catalysts.