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 (CeOx)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 (CeOx)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-NOx, which could be inferred as important clues to innovate more efficient catalysts for NH3-SCR-NOx, as well as other heterogeneous catalysis applications based on Cu-catalysts.