Regeneration of Al2O3-Coated Cordierite Supported CuO for Simultaneous SO2 and NO Removal

Al2O3-Coated cordierite supported CuO catalysts exhibit desirable activities for simultaneous SO2 and NO removal from flue gas at 400 (degree) C. This paper aims to investigate their regeneration behavior when it is conducted in 5% NH3/Ar at 400 (degree) C. N2 adsorption, scanning electron microscopy (SEM), temperature-programmed reduction (TPR), chemical analysis, extended X-ray adsorption fine structure (EXAFS), and X-ray diffraction (XRD) techniques are used in the study. Results show that a small amount of sulfates located in some of the pores of the catalysts cannot be reduced by NH3 at 400 (degree) C, which results in significant decreases in surface area and pore volume of the catalyst. This, in turn, reduces the mass transfer rate of SO2 and makes some of the reduced copper not reachable by SO2 in the time frame of the experiment (SO2 conversion of greater than 70%). These are responsible for the decrease in SO2 removal activity after the regeneration. Water washing of the catalyst after the first regeneration may remove the unreduciable sulfates and improve SO2 removal activity of the catalyst in the subsequent cycles. Regeneration and water wash do not influence NO removal activity, and the washed catalyst can run stably at high activities for SO2 and NO removal.