Directional anchoring silver nanoparticle strategy to enhance MIL-101(Cr) for mercury removal from coal-fired flue gas: Experimental and theoretical insights

To enhance the elimination of trace elemental mercury (Hg 0 ) from coal-fired flue gas, silver nanoparticles (AgNPs) were directionally anchored into the pores of MIL-101(Cr) using the double-solvent method (DSM) to achieve a highly dispersed fixed-bed adsorbent Ag@MIL-101 at room temperature. Various experimental characterizations were conducted to verify the Physical and chemical properties of the adsorbent, and fixed bed adsorption experiments evaluated the Hg 0 removal efficiency. Within the temperature range of 30–70 °C, Ag@MIL-101(Cr) achieved nearly 100 % Hg 0 removal efficiency, maintaining stability even at high concentrations of SO 2 (1500 ppm) and H 2 O (9 %). Density functional theory (DFT) revealed that the introduction of AgNPs greatly enhanced the adsorption capacity of MIL-101(Cr) for Hg 0 , with an evident electron exchange between Ag and Hg, and the adsorption energy changed from −36.91 kJ/mol to −68.59 kJ/mol. The interaction between Ag and Hg was a relatively strong weak interaction, which allowed for easy desorption at moderate temperatures (∼200 °C), significantly saving energy. Tests conducted with flue gas from an actual coal-fired power plant demonstrated that 2Ag@MIL-101(Cr) exhibited superior Hg 0 removal efficiency compared to activated carbon at the WESP outlet under low-temperature (about 50 °C) and high-humidity conditions, providing an efficient and economical solution for flue gas purification.