Enhanced resistance to K poisoning and SO2 & H2O on Ce0.63TiOx catalyst by sulfation treatment

At present, alkali metal poisoning is still a problem should be solved for catalyst deactivation of selective catalytic reduction (SCR) of NOx with NH3. In this work, the Ce0.63TiOx (CT) catalyst was synthesized by hydrothermal method and it was used the wet immersion method of H2SO4 treatment to obtain CT-xwt%S catalysts. The NH3-SCR denitrification (de-NOx) activity, resistance to SO2 & H2O and K-resistant properties of catalysts were studied, and the catalysts were characterized by N2 physical adsorption, XRD, Raman spectroscopy, TEM images, NH3-TPD, H2-TPR, NO-TPD, XPS, IR spectra of pyridine adsorption and in situ DRIFTS. The experimental results show that CT-0.5 wt%S catalyst has stronger resistance to K, H2O and SO2 than CT catalyst. Although the redox performance of the CT-0.5 wt%S catalyst is reduced, the sulfation treatment increased the surface acidity, which promoted the adsorption and activation of ammonia. This facilitates the high-temperature activity of CT-0.5 wt%S catalyst and enhances the K resistance of the catalyst. Satisfyingly, the strong interaction between K species and SO42− in the CT-0.5 wt%S catalyst protects the active sites to K poisoning. In addition, in situ DRIFTS results indicate that K poisoning depletes the acid sites, and the rich acid sites of CT-0.5 wt%S catalyst can be used as sacrifices site to coordinate with K, thus weakening the influence of K poisoning on catalyst. This work provides a new strategy for designing NH3-SCR catalysts with excellent resistance to K.