Simultaneous Adsorption of Gaseous Hg0 and Hg(II) by Regenerable Monolithic FeMoSx/TiO2: Mechanism and its Application in the Centralized Control of Hg Pollution in Coal-Fired Flue Gas

FeMoSx/TiO2 was investigated as a regenerable sorbent to simultaneously adsorb Hg-0 and Hg(II) from coal-fired flue gas for the centralized control of Hg pollution discharged from coal-fired power plants. The performance of FeMoSx/TiO2 for Hg(II) and/or Hg-0 adsorption was evaluated on a fixed-bed reactor at 80 degrees C, and the mutual interference between Hg-0 adsorption and Hg(II) adsorption was analyzed using individual adsorption, simultaneous adsorption, and two-stage adsorption. FeMoSx/TiO2 displayed an excellent capacity for individual Hg-0 adsorption (41.8 mg g(-1)) and a moderate capacity for individual Hg(II) adsorption (0.48 mg g(-1)). Two types of adsorption sites were present on FeMoSx/TiO2 for gaseous Hg adsorption (S-0 and FeS2/MoS3 sites). X-ray photoelectron spectroscope and kinetic analyses demonstrated that Hg-0 and Hg(II) could adsorb onto S-0 sites, whereas only Hg-0 was adsorbed onto FeS2/MoS3 sites. As He competed with Hg(II) for the S-0 sites, the amount of Hg(II) adsorbed slightly decreased by 16% in the presence of Hg-0. However, He adsorption onto the FeS2/MoS3 sites predominated over the Hg-0 adsorption onto FeMoSx/TiO2 and it was not inhibited in the presence of Hg(II). Therefore, the amount of Hg-0 adsorbed on FeMoSx/TiO2 was only decreased by 2% in the presence of Hg(II).

Automated summary

FeMoSx/TiO2 was investigated as a regenerable sorbent for simultaneous adsorption of Hg-0 and Hg(II) from coal-fired flue gas. It exhibited excellent capacity for Hg-0 adsorption and moderate capacity for Hg(II) adsorption.