Boosting NO removal performance of selective catalytic reduction with NH₃ on hydrotalcite derived NiCuFe mixed oxides synthesized via urea hydrothermal method

NiCuFe layered double oxide (LDO) catalysts were synthesized using co-precipitation, impregnation, and urea hydrothermal methods. The NH₃-SCR activity of NiCuFe-LDO catalysts was investigated to determine the effect of different synthesis methods. All NiCuFe-LDO samples exhibited good catalytic performance at low temperatures, with the sample synthesized using the urea hydrothermal method (NiCuFe-LDO-3) being the most efficient catalyst. The NiCuFe-LDO-3 catalyst achieved over 80% NO conversion in the temperature range of 180 °C to 280 °C, with a peak of 95.13% at 240 °C. The physicochemical properties of the samples were systematically characterized using XRD, SEM, BET, NH₃-TPD, H₂-TPR, XPS, and in-situ DRIFTS. The results showed that the NiCuFe-LDO-3 sample had the best crystallinity, as demonstrated by XRD and SEM. BET analysis revealed that the NiCuFe-LDO-3 sample had the largest specific surface area. The NiCuFe-LDO-3 sample was found to have more acidic sites and a better redox capacity than the other samples, according to the H₂-TPR and NH₃-TPD results. In-situ DRIFTS analysis showed that the catalyst operates through both E–R and L–H reaction mechanisms.