Regeneration of the Waste Selective Catalytic Reduction Denitrification Catalyst by Nitric Acid Washing.

In this study, the waste VO-WO/TiO denitrification catalysts from the coal-fired power plant were washed with water or nitric acid, followed by impregnating different contents of VO. The effects of the HNO concentration and the additional amount of vanadium on the low-temperature selective catalytic reduction denitrification activity were investigated under the condition of high concentration of SO and HO. The catalysts were characterized by inductively coupled plasma optical emission spectrometry, X-ray powder diffraction , N adsorption/desorption, H-temperature-programmed reduction, NH-temperature-programmed desorption , Fourier transform infrared spectroscopy , and Raman spectroscopy. The evaluation results revealed that optimum activity was achieved by using 0.8 mol/L HNO solution and loading 1.60 wt % VO to make the total VO reach 2.3 wt %. The characterization results showed that nitric washing can remove most of the ammonium salts deposited on the surface of the waste catalyst and produce crystalline WO, which can effectively inhibit the agglomeration of vanadium species in the process of impregnation. Furthermore, it can also increase the amount of oligomeric VO , which can improve the denitration activity.