Tuning surface acids and electron transfer behavior by CeO2 modification to enhance reactivity of CuCoFe-LDO catalysts for C3H6-SCR: Characterization, in situ DRIFTS and DFT+ U.

Developing efficient catalysts with excellent low-temperature activity and poisoning resistance is critical for advancing C3H6-SCR technology. A series of Cex-CCF-LDO catalysts were prepared via a one-step co-precipitation method. The CeO2 modification strategy significantly boosts the catalytic performance of CuCoFe-LDO. The optimized Ce0.15-CCF-LDO delivers 88.1% NO conversion and 98.2% N2 selectivity at 250 °C, and its NO conversion experiences a further increase after SO2 introduction. Combined with multiple characterizations, in situ DRIFTS and DFT calculations, the performance promotion and sulfur tolerance mechanisms of CeO2 modification were systematically clarified. CeO2 modification markedly increases specific surface area, pore volume and oxygen vacancy concentration. The downshifted reduction temperature and doubled acid content are crucial for the improved low-temperature and overall catalytic performance. The 3d-2p-5d orbital hybridization verifies electronic interactions between Ce and transition metals, which strengthens NO and O2 adsorption. Ce sites also exhibit lower energy barriers for O2 dissociation and NO2 formation. R-NCO hydrolysis serves as the critical step in the C3H6-SCR cycle over Ce0.15-CCF-LDO. Ce2(SO4)3 formed at Ce sites facilitates the partial oxidation of C3H6, yields more reactive intermediates and new species, and thus accelerates the SCR reaction. This work provides a feasible strategy for the rational design of C3H6-SCR catalysts.