Elemental Mercury Removal from Coal-Fired Flue Gas on Sulfur-Modified Activated Biomass Coke: Experiment and Simulation

Abstract

It is necessary to find a better method to remove mercury from coal-fired flue gas. This work proposes the use of corn stalk coke to remove mercury from coal-fired flue gas and through elemental sulfur (CSC-S), water vapor activation (CSC-H2O), and sulfur modification combined with water vapor activation (CSC-H2O-S) to prepare three different adsorbents. The mercury removal performance of the adsorbents prepared by different methods was evaluated on a small fixed-bed mercury removal experimental platform. The experimental results showed that the order of mercury removal efficiency of the four adsorbents was: CSC-H2O-S > CSC-S > CSC-H2O > CSC. Brunauer–Emmett–Teller (BET), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) were adopted to study the physical and chemical properties of the adsorbent surface and the mechanism of mercury removal. The results showed that water vapor activation can improve the pore structure of the adsorbent, increase its specific surface area, and generate new oxygen-containing functional groups on the surface of the adsorbent. The adsorption kinetic model further demonstrated that the water vapor activation process can improve the physical adsorption performance of corn stalk char, and the sulfur modification process can improve the chemical adsorption performance of corn stalk char. Quantum chemical studies have shown that the surface structure doped with S and O atoms is conducive to enhancing the adsorption of Hg0.