A novel LDO@M catalyst for SCR-C3H6: Boosting N2 selectivity and inhibiting SO42- formation

• LDO@M catalyst exhibits higher N 2 selectivity and a wider reaction temperature window compared to the pure LDO catalyst. • The hybridization increases the content of Cu 2+ , vacancy oxygen, and acid site, but decreases the lattice oxygen content. • The hybridization enhances the formation of -CN and R-NCO species while inhibiting the generation of SO 4 2- . • Alongside the proposed reaction pathway, the discrepancies in specific reaction pathways on different catalysts are also pointed out. To overcome the limitations of conventional LDHs (Layered Double Hydroxides) derived catalysts, composite LDO@M (M=Al 2 O 3 , SiO 2 ) catalysts derived from Cu 0.5 Ni 1.5 Fe 1 -LDHs@M were synthesized. Compared to the pristine LDO catalyst, albeit with a minor trade-off in low-temperature activity, LDO@M catalysts significantly boost N 2 selectivity and medium-high temperature activity, especially the LDO@Al 2 O 3 catalyst. Comprehensive characterization elucidates this complex activity performance. According to XRD and XPS results, the hybridization induces the segregation of CuO and modulates the surface chemical state, characterized by an enrichment of Cu 2+ species and oxygen vacancy alongside a decline in Cu + and lattice oxygen, thereby enhancing the N 2 selectivity with a minor trade-off in low-temperature activity. BET and Py-FTIR results reveal that the hybridization generates micropores and Brønsted acid sites, along with improving specific surface area and surface acidity, which effectively mitigates the competitive adsorption of H 2 O and SO 2 . In situ DRIFTS reveals the suppression of SO 4 2- species accumulation caused by the hybridization, the difference in types and accumulation of active intermediates (e.g., monodentate and bidentate nitrates, acetate, -CN, R-NCO) across all catalysts. Ultimately, based on TPSR experiments, the specific SCR-C 3 H 6 reaction pathways and their variations across all catalysts are established.