Effect of SO(2) on the Selective Catalytic Reduction of NO(x) over V(2)O(5)-CeO(2)/TiO(2)-ZrO(2) Catalysts

The effect of SO(2) on the selective catalytic reduction of NO(x) by NH(3) over V(2)O(5)-0.2CeO(2)/TiO(2)-ZrO(2) catalysts was studied through catalytic activity tests and various characterization methods, like Brunner−Emmet−Teller (BET) surface measurement, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray fluorescence (XRF), hydrogen temperature-programmed desorption (H(2)-TPR), X-ray photoelectron spectroscopy (XPS) and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS). The results showed that the catalyst exhibited superior SO(2) resistance when the volume fraction of SO(2) was below 0.02%. As the SO(2) concentration further increased, the NO(x) conversion exhibited some degree of decline but could restore to the original level when stopping feeding SO(2). The deactivation of the catalyst caused by water in the flue gas was reversible. However, when 10% H(2)O was introduced together with 0.06% SO(2), the NO(x) conversion was rapidly reduced and became unrecoverable. Characterizations indicated that the specific surface area of the deactivated catalyst was significantly reduced and the redox ability was weakened, which was highly responsible for the decrease of the catalytic activity. XPS results showed that more Ce(3+) was generated in the case of reacting with SO(2). In situ DRIFTS results confirmed that the adsorption capacity of SO(2) was enhanced obviously in the presence of O(2), while the SO(2) considerably refrained the adsorption of NH(3). The adsorption of NO(x) was strengthened by SO(2) to some extent. In addition, NH(3) adsorption was improved after pre-adsorbed by SO(2) + O(2), indicating that the Ce(3+) and more oxygen vacancy were produced.