Highly dispersed Mn and Cu on LDO/Z composite catalysts with strong H2O resistance for low-temperature NH3-SCR

A novel catalyst of Cu-Mn layered structure oxides loading on zeolite (LDO/Z) was prepared via co-precipitation method for low-temperature selective catalytic reduction of NO with NH3 (NH3-SCR), which presented NOx conversion of 97 % and N2 selectivity of 99 % at 175 degrees C with the GHSV of 45000 h- 1. Impressively, it exhibited significant resistance to H2O due to the existence of particular hydrophobic structure. The catalysts were characterized comprehensively with respect of X-ray diffraction (XRD), Scanning elec-tron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR), NH3 temperature programmed desorption (NH3-TPD) and in situ DRIFTS. The superior NH3- SCR performance of LDO/Z catalyst could be related to the well dispersion of Mn and Cu oxides, higher reducibility in low temperature, and abundance of acid sites, high adsorbed oxygen (abundant active Ov) and the presence of electron transfer between the Cu+ and Mn4+ redox cycles & sdot;NH3-SCR over LDO/Z followed "Langmuir-Hinshelwood" (L-H) and "Eley-Rideal" (E-R) mechanism with occurrence of "Fast-SCR" reaction. This work provides an approach to develop H2O-resistant catalysts, which has implication for practical applications in flue gas NOx removal.