DeNO_x performance of Cu–Mn composite catalysts prepared by the slurry coating method

Abstract

In this study, Cu–Mn composite catalysts were prepared by the slurry coating method using honeycomb cordierite as a support and TiO₂ as a carrier. The influence of the relative composition of Cu, Mn on the DeNO_x performance was studied for different preparation processes. It was found that the catalyst prepared by adding 15 wt% Mn and 5 wt% Cu into the slurry at the same time has higher conversion than that of the catalyst only using Mn as the active component. For the composite catalyst prepared by loading Mn and Cu onto TiO₂ followed by the complex of MnO_x/TiO₂ and CuO_x/TiO₂ (weight ratio of 2:1) powder, a high activity is achieved in a temperature range, which can be due to the weak interaction between Cu and Mn. The considerable denitrification of the catalyst should be attributed to the large surface area and pore volume, uniform distribution, higher activity Mn in the form of MnO₂ and synergy of Mn, Cu and carrier. The catalyst prepared by two methods were characterized by XRD, XPS, SEM and H₂ temperature-programmed reduction (H₂-TPR). H₂-TPR results reveal that the interaction between Cu and Mn varies with the change of the composition of two components. XPS results illustrated that the relative atomic percentage values of n(Mn⁴⁺)/n(Mn³⁺) and n(Mn⁴⁺)/n(Mnⁿ⁺) were significantly high for the catalyst with better catalytic performance and the MnO₂ is the dominant phase with respect to the Mn₂O₃ and MnO phase in all catalysts. Meanwhile, we can draw the conclusion that the MnCu/ZTC catalyst by the mixed loading way is superior to TMnCu/CC through the order loading method by XPS and NH₃-SCR test.