Insight into the Mercury Removal Mechanism of Copper Salt-Modified Biomass Coke in an Oxyfuel Combustion Atmosphere

The development of effective sorbents using biomass is important to achieve mercury removal in coal combustion flue gas. In this work, a biomass sorbent was prepared by using rice husk as a raw material and CuCl2 solution as a modifier. The experiment explored the mercury removal ability of rice husk with different modification solution concentrations. The sorbent showed the best mercury removal capacity with 0.15 mol/L CuCl2 solution modified rice husk coke at an inlet mercury concentration of 54.4 μg/m3 at 150 °C. It was found that the modification made CuCl2 adhere to the surface of the coke sample successfully and chlorine-containing functional groups and copper-containing functional groups in the coke sample both promoted the adsorption of mercury. The increase in chemisorbed oxygen due to the modification also promoted the sorbent removal of mercury. The increase of adsorption temperature and inlet mercury concentration was beneficial to mercury removal, but too high temperature had a negative effect on its mercury removal. The purpose of this work is to explore a novel approach for the efficient use of this agricultural waste, apply it to mercury removal in oxyfuel coal-fired power plants, and provide technical support and theoretical guidance for its application in industry.