Influence of sodium on deactivation and regeneration of SCR catalyst during utilization of Zhundong coals

Zhundong coals have a super huge reserve and many excellent characteristics. However, the sodium content in Zhundong coal is extremely high, which can accelerate the deactivation of the V-W-TiO2 selective catalytic reduction (SCR) catalysts. In the present work, the solution impregnation method was adopted to investigate the effect of alkali metals deposition on the SCR catalysts, while various approaches were employed to regenerate the poisoned catalysts. Experimental results indicate that sodium deposition significantly deactivates the catalytic performance of SCR catalysts and sodium hydroxide (NaOH) presents the most serious deactivation. The catalytic ability of sodium poisoned catalyst is only slightly recovered by water washing, whereas it could be improved to approach that of the fresh catalyst by acid solution washing. The regeneration effect of sulfation with SO2 is between those of water washing and acidic solution washing. Further characterizations validated that the deactivation is mainly caused by the damage of surface acid sites. Acidic solution can remove more than 75 wt% of the deposited sodium and provide new acid sites on catalyst surface. Therefore, acidic solution washing is a satisfactory method to regenerate poisoned SCR catalysts for power plants firing high-sodium coals. (C) 2016 Curtin University of Technology and John Wiley & Sons, Ltd.