Mechanism of N2 formation over the FeO-MnO2/SiO2 (100) surface in low-temperature NH3-SCR process: Electronic analysis of reaction pathways and key intermediates

Abstract

Density Functional Theory (DFT) was used to study the process and details of N₂ formation on the FeO-MnO₂/SiO₂ (100) surface during selective catalytic reduction of NH₃ (NH₃-SCR). The Fe and Mn sites on the surface of the FeO-MnO₂/SiO₂ (100) play important roles in denitrification. NH₃ forms stable chemical adsorption on its surface, especially with stronger adsorption capacity on the Fe sites than on the Mn sites. Furthermore, Fe sites demonstrate better performance in NH₃ dehydrogenation reactions in comparison to Mn sites, but the key intermediate NH₂NO tends to form on the Mn sites. NH₂NO may generate N₂ through a dehydrogenation reaction at the Fe sites on the catalyst surface, while it is more inclined to decompose and generate N₂ through internal migration on the Mn sites. These results help to deepen the understanding of the micro-mechanism of catalysts in N₂ generation, laying a theoretical foundation for improving the denitrification performance and N₂ selectivity of catalysts.