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

Abstract

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 °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.