A combined DFT calculation and experimental study of the mechanism of the SCR of NO by NH over Fe-doped CoMnO.

NH selective catalytic reduction (SCR) is a promising method for NO removal, but its low-temperature effectiveness and narrow operating window limit industrial use. This study demonstrates, through DFT calculations and experimental validation, that Fe-doped CoMnO (CoFeMnO) catalysts can effectively enhance catalytic activity. Through the in-depth study of NH-SCR, it was found that the NH adsorption on the catalyst surface might be significantly enhanced by the doping of Fe ( = -1.29 eV → -1.42 eV), and it was also further demonstrated that the NH had a better adsorption energy on the surface of the CoFeMnO catalyst through the electron difference density (EDD) and partial density of states (PDOS). In addition to this, the CoFeMnO catalyst not only reduces the first step of the dehydrogenation reaction of NH ( = 0.86 eV → 0.83 eV), but also lowers the energy barrier of the NH-SCR ( = 1.11 eV → 0.86 eV). All these calculations demonstrate that Fe doping has the potential to significantly enhance catalytic performance. CoMnO and Fe-doped CoMnO (CoFeMnO) catalysts were synthesized using sol-gel and impregnation techniques, respectively. Through characterization and performance testing, CoFeMnO is found to exhibit a more efficient NO conversion (87% at 250 °C), and its N selectivity is also slightly improved (64%), which matches with the calculation results. In this study, a method to improve the denitrification efficiency of CoMnO spinel catalysts was proposed, which provides a new idea for the development of CoMnO catalysts.