A combined DFT and experimental study of NO by NH-selective catalytic reduction over an Fe-doped CoAlO catalyst

The selective catalytic reduction of NO x by NH 3 (NH 3 -SCR) has garnered significant attention. However, the industrial application of the catalysts is limited due to their poor low-temperature activity and narrow operation window. In this study, we have elucidated that Fe doping significantly improves the low-temperature NH 3 -SCR activity of CoAl 2 O 4 catalysts at the atomic level by means of density functional theory calculations and experimental measurements. The structures of the low-refractive index (100) surface of both intrinsic CoAl 2 O 4 and Fe-doped CoAl 2 O 4 catalysts, as well as the adsorption models for molecules such as NH 3, were computationally determined. In addition, the reaction process of NO x removal by NH 3 was investigated thoroughly. The results showed that the adsorption energy of NH 3 increased after Fe doping. It is noteworthy that the doped Fe site is also a strong active site for the catalytic reaction. Moreover, the first dehydrogenation step of NH 3 is a rate-determining step (0.82 eV), and Fe doping also significantly reduces the NH 3 -SCR reaction path energy barrier (0.67 eV). Intrinsic CoAl 2 O 4 and Fe-doped Fe-CoAl 2 O 4 catalysts were prepared by hydrothermal and impregnation methods. The results showed that the Fe doped CoAl 2 O 4 catalyst could significantly enhance its denitrification catalytic activity, thereby indicating the excellent selectivity of the Fe-CoAl 2 O 4 catalyst, which is consistent with the calculated results. The present study presents a novel approach to enhance the catalytic efficiency of CoAl 2 O 4 denitrification, thereby facilitating the development of CoAl 2 O 4 spinel-based catalysts with superior performance. This research unveils the environmental importance of Fe-doped CoAl 2 O 4 catalysts, enhancing low-temperature NH 3 -SCR for cleaner air quality and reduced emissions.