Structure-activity relationships, product species distribution and the mechanism of effect of multi-component flue gas on Hg adsorption and oxidation over CuO/ACs.

A series of Cu-doped activated cokes (CuO/ACs) were synthesized an impregnation method and applied for the removal of elemental mercury (Hg). Structure-activity relationships between Hg removal and CuO/AC surface characteristics were identified. Hg removal over CuO/AC occurs through a combination of physisorption and chemisorption and is mainly dominated by chemisorption. It was found that 1 nm micropores facilitate Hg physisorption. Hg could weakly adsorb onto an O-terminated crystal layer, whereas strongly adsorb onto Cu-terminated single highly dispersed, clustered and bulk CuO (110) crystal planes the Mars-Maessen mechanism. Product distributions and mechanisms of Hg adsorption and oxidation over the CuO/AC catalyst under multi-component flue gases are also discussed. O enhances both physisorption and chemisorption toward Hg by 38%. Inhibition of Hg removal by SO originates from the competitive adsorption and deactivation of CuO cation vacancies, whereas the impact is weakened by O through generating 20% of physically adsorbed mercury product species. NO and O promote Hg chemisorption efficiency by 93% to form Hg(NO). HOCl and/or Cl produced by HCl can oxidize 100% of Hg to HgCl, and the catalytic oxidation efficiency is approximately 29%, but O slightly lowers the Hg catalytic oxidation efficiency by 8%. The affinity ability between various flue gases and Hg follows the order O < NO < HCl.