Thiol-grafted MnOx/TiO2 as a dual-site adsorbent for removal of Hg0 from simulated coal-fired flue gas

Emissions of elemental mercury (Hg0) from coal-fired power plant have become a great threaten to the ecosystems. Adsorption is a practical strategy for abating Hg0, but limited Hg0-targeted sites is a stumbling block to developing high-efficiency adsorbents. This work aims to design an efficient adsorbent for Hg0 purification at high gas hourly space velocities (GHSV) is achieved by co-implanting porous TiO2 with inorganic-organic dual functional sites (-SH and MnOx). The 2SH-MnOx/TiO2 prepared at -SH: MnOx ratios of 2:6 is demonstrated a Hg0 removal efficiency of 90 % at 175 degrees C under a GHSV of 120,000 h-1. Based on Hg-Temperature Program Desorption (Hg-TPD) analysis, the adsorbed Hg0 converted to HgS and HgO at the -SH and MnOx sites of the adsorbents, respectively. The existence of MnOx was revealed to facilitate the generation of HgS. Theoretical calculations suggested that the co-existence of -SH and MnOx promotes Hg0 adsorption and boost electrons transfer from Hg0 to adsorbent surface. This study provides a new prospect in developing an advanced alternative adsorbent to increase the efficiency of Hg0 removal from coal-combustion flue gas.