High Efficiency of Ce-Modified MnOx/TiO2-ZrO2-Based Low-Temperature Selective Catalytic Reduction Denitration Catalysts

Abstract

The Mn-based denitration catalyst has problems such as structural instability and poor poison resistance. In this work, Ce-modification improved the NOx conversion and sulfur resistance of Mn-based catalysts. The TiO2-CeO2, ZrO2-CeO2 and TiO2-ZrO2-CeO2 (molar ratio of 4∶1∶n) carriers were prepared by the sol–gel method, then MnOx was impregnated on TiO2-ZrO2-CeO2 to investigate the catalytic activity and SO2 resistance at low temperature. The as-synthesized catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetry (TG) to show the microstructure of the catalyst and the effect of Ce on the denitration performance. The results demonstrated that the addition of Ce into the TiO2-ZrO2 carrier inhibited the growth of TiO2 grains, formed CeTi2O6 crystals, improved the content of Mn4+, and increased the adsorption of NH3, and thus the NOx conversion efficiency was improved. In the presence of both SO2 and H2O, the addition of Ce lowered the formation amount of ammonium sulfate and avoided the sulfation of manganese. The results suggest that Ce improved the structural instability and poison-resistance of Mn-based catalysts.