New insights into the effects of potassium species on the Hg0 removal performance of MnOx/HZSM-5 adsorbent

In this article, the effects of K species, including K 2 O, KCl, and K 2 SO 4 , on the Hg 0 removal capability of MnO x /HZSM-5 adsorbent were investigated. Adding K 2 O and K 2 SO 4 interfered with the Hg 0 removal process; as the loading amount of these two K species increased, this adverse impact became more obvious. This was because the added K 2 O or K 2 SO 4 lowered the acidity and oxidizability of the adsorbents via the interactions with MnO x , which exerted an inhibitory effect on the adsorption and oxidation of Hg 0 . By contrast, introducing KCl made almost no adverse impacts on the Hg 0 elimination ability of the adsorbents. With rising the KCl content to 4 wt%, even ∼92.7% Hg 0 removal efficiency was obtained. This could be attributed to the presence of Cl − ; with the guidance of high-valence-state metal cations and O 2 , Cl − could be converted to active chlorine species, which was capable of transforming Hg 0 to HgCl 2 . This finding supplied a theoretical basis for developing new adsorbents that were capable of stably operating in the power plants with high-alkali-content coal utilized.