Enabling Coal-Fired Power Flexibility: Wide-Temperature NOx Removal via Strong Electron–Orbital Interaction in Dual-Site Catalysts

The narrow operating temperature window of commercial V-W/TiO2 catalysts severely limits NOx removal efficiency, especially during low-load boiler operations. To achieve broad-temperature NOx abatement, we developed Ce-M/Ti (M = Co, Fe, Mn, Mo) catalysts via a dual-site strategy. The temperatures required for 80% NO conversion (T80) were 302 °C for Ce-Mo/Ti, 372 °C for Ce-Fe/Ti, 393 °C for Ce-Mn/Ti, and 415 °C for Ce-Co/Ti. Among them, Ce-Mo/Ti exhibited the most favorable low-temperature activity, outperforming a commercial catalyst (324 °C). Its turnover frequency (3.12 × 10−3 s−1) was 1.29 times higher. Combined physicochemical characterization and density functional theory (DFT) calculations further reveal the mechanism behind the enhanced dual-site synergy in Ce-Mo/Ti. In the Ce-Co, Ce-Fe, and Ce-Mn sites, weak orbital hybridization leads to limited charge transfer. In contrast, Ce-Mo/Ti exhibits stronger hybridization between the Ce 4f/5d and Mo 4d orbitals, which breaks the inherent limitation of the Ce-based (Ce3+/Ce4+) redox capability and enables reverse electron transfer from Mo to Ce. This distinctive electron transfer direction creates a unique electronic environment, activating an efficient redox cycle between Mo6+/Mo5+ and Ce4+/Ce3+. This work offers a promising design strategy for dual-site catalysts with high NOx removal efficiency over a wide temperature range.