Regeneration characteristics of Ca-poisoned commercial selective catalytic reduction denitrification catalyst

Alkaline earth metal calcium is a typical poison in coal-fired power plants, which will result in deactivation of SCR catalyst. The ATMP (amino trimethylene phosphonic acid) and PBTCA (2-phosphonobutane-1,2,4-tricarboxylic acid) complexing agents were employed for the regeneration of a poisoned by calcium V₂O₅-WO₃/TiO₂ catalyst. The physical and chemical properties and regeneration denitration performance of the catalyst before and after regeneration were investigated by BET, NH₃-TPD, H₂-TPR, XPS and experiments. The results indicated that the ATMP and PBTCA exhibited efficient regeneration performance, and the NO_x conversion of regenerating catalysts recovered from 25.8% to 89.8% and 88.1% at 400 ℃, respectively. Compared with the regeneration by dilute sulfuric acid, the ATMP and PBTCA exhibited a higher calcium removal rate with lower vanadium loss (less than 5%). The utilization of the ATMP and PBTCA can effectively restore the Brønsted acid sites, active vanadium V^{5 +} and the surface chemisorbed oxygen O_α on the catalyst surface, which leads to the overall activity of the catalyst reaching an optimal level. Therefore, it has a great potential to apply ATMP and PBTCA complexing agents in the regeneration of deactivated SCR denitration catalysts.