Modulating Cu+ distribution on the surface of Ce-doped CuO composite oxides for SO2-resistant NH3-selective catalytic reduction of NO

Abstract

A series of (CeO_x)_mCuO composite oxides with different Ce/Cu molar ratios (m) were prepared by co-precipitation for ammonia-selective catalytic reduction of NO (NH₃-SCR-NO) in the absence and presence of SO₂. Through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), H₂-temperature programmed reduction (H₂-TPR), and NH₃-temperature programmed desorption (NH₃-TPD) characterization, it was demonstrated that the prepared samples were featured by distinguished Cu⁺ distributions on the surface of the Ce-doped CuO composite structure, indicating a special interaction or synergistic effect present in the samples. The modulated distributions of Cu⁺ achieved by adjusting the Ce/Cu molar ratio were found to be crucial for optimizing the redox ability and acid feature among the samples. The outstanding SO₂-resistant NH₃-SCR-NO performance (NO conversion close to 100% in temperature window of 250–350 °C under 200 ppm SO₂-presence) was observed on (CeO_x)_0.25CuO which possessing the highest Cu⁺ distribution, indicating the significant dependence of Cu⁺ distribution in Cu-based catalysts on enhancing catalytic performance for NH₃-SCR-NO. These results also suggested that the distinguished synergistic effect among binary component Cu-based catalysts should be considered as an important factor to govern the performance of NH₃-SCR-NO_x, which could be inferred as important clues to innovate more efficient catalysts for NH₃-SCR-NO_x, as well as other heterogeneous catalysis applications based on Cu-catalysts.