A Study on the Offset Deactivation Effect of Potassium and Phosphorus on MnEuO _x SCR Catalyst

In this study, a remarkable offset deactivation effect of K and P on MnEuOx SCR catalyst has been found. Experimental results showed that the NO conversion over K−P poisoned catalyst was close to 80 % at 250 °C. Several characterization techniques containing NH3-TPD, XPS, H2-TPR, XRD and in situ DRIFT were used to reveal the mechanism of the offset effect. The characterization of NH3-TPD and H2-TPR suggested that the introduction of P on MnEuOx-K could improve its surface acidity and redox ability. Moreover, the content of chemisorbed oxygen and Mn4+ were markedly restored under the situation that the toxic elements were coexistent on catalyst surface. The strong interaction between K and P might be the major reason for the offset deactivation effect. More specifically, PO3− species were preferentially bonded with the surface potassium species and released MnO2 active sites poisoned by K. Therefore, the highly active MnO2 sites might be protected and the catalytic activity could be restored.