Trimetallic FeNiCu\nAtomic Clusters Supported on Carbon\nMatrix: Highly Active Catalysts for C<sub>3</sub>H<sub>6</sub>–SCR\nof NO

C<sub>3</sub>H<sub>6</sub>–SCR denitrification\ntechnology\nfaces catalyst deactivation problems and low catalytic performance\nat medium-low temperatures. This study utilized the intermetallic\nsynergies to prepare atomic cluster catalysts (FeNiCu/NC) by anchoring\nFe–Ni–Cu on a carbon matrix to enhance the C<sub>3</sub>H<sub>6</sub>–SCR performance at medium-low temperatures.\nThe synergistic effect of the Fe–Ni–Cu is reflected\nin the differences in the physicochemical properties of the catalysts,\nwhich is proved by several characterization techniques. Results showed\nthat the FeNiCu/NC catalyst had a larger surface area (541.4 m<sup>2</sup>/g) and there were no metal oxides on the surface of the catalyst\nbut abundant defective sites that anchored Fe/Ni/Cu atoms through\nN atoms to form M–N<sub><i>x</i></sub> active sites\nand atomic clusters. The hollow carbon morphology provides sufficient\nactive sites for C<sub>3</sub>H<sub>6</sub>–SCR. The coordination\nenvironments of active sites were M–N<i><sub>x</sub></i>–C, Fe<sub>2</sub>/FeCu<sub>2</sub>/FeNi<sub>2</sub>, Ni<sub>3</sub>/NiFe/NiCu<sub>2</sub>, and Cu<sub>4</sub>/CuFe<sub>2</sub>/CuNi<sub>2</sub>, where the synergistic action of trimetal leads\nto the presence of Fe–Ni–Cu–N<sub><i>x</i></sub>–C. The synergistic action of the Fe–Ni–Cu\nsignificantly improved the C<sub>3</sub>H<sub>6</sub>–SCR performance\nat medium-low temperatures. The FeNiCu/NC exhibited an 81% NO conversion\nat 150 °C under 2% O<sub>2</sub>, 15% and 20% higher than FeNi/NC\nand FeCu/NC catalysts, respectively. Even at 4% O<sub>2</sub>, the\nFeNiCu/NC catalyst was active to remove 78% NO and achieve a 93% N<sub>2</sub> selectivity at 150 °C and maintained a 100% NO conversion\nat 300–425 °C. The DRIFTS results demonstrated that NO\nand C<sub>3</sub>H<sub>6</sub> could combine with active O at metal\ncluster, M–N<sub><i>x</i></sub>, or defective oxygen\nsites to produce various intermediate species, wherein acetates and\nnitrates were the main active intermediates. Based on the DRIFTS results,\na reaction pathway for C<sub>3</sub>H<sub>6</sub>–SCR over\nthe FeNiCu/NC catalyst was proposed.