Magnetic biochar has been proven to be an efficient adsorbent for the removal of elemental mercury (Hg). However,SO2、NO and HCl are acid components of the oxyfuel combustion flue gas,and their roles in magnetic biochar removal of Hg have not beendetermined. By simulating an experimental setup with oxyfuel combustion atmosphere, the effects of acidic gas concentration on theadsorption and oxidation efficiencies of Hg at different reaction temperatures,as well as the thermal regeneration cycling performance ofmagnetic biochar,were thoroughly investigated. The results showed that 0.4% SO2 promoted the adsorption of Hg by magnetic biocharwith 93.5% Hg removal at 120 °C,but higher concentrations of SO2 (>0.4%) produced an inhibitory effect and promoted the oxidation of a small amount of Hg,which partially alleviated the inhibitory effect of SO2 on the adsorption of Hg. Meanwhile,NO shows a similar pattern in oxyfuel combustion atmosphere. Gaseous HCl is an important accelerator,and the mercury removal rate in the presence of0.02% HCl is close to 100%,which counteracts the adverse effects of flue gas components. However,the pattern of action of SO2 on Hg removal from magnetic biochar at high temperatures was similar to that at 120 ℃. At 350 ℃,1.6% SO2 inhibited Hg adsorption evenmore,with an adsorption efficiency of only 19.5%,which was lower than the efficiency of Hg oxidation,and mainly generated more oxygen-containing functional groups such as CO; NO also showed strong inhibition at high temperatures,and the rate of mercuryremoval gradually decreased with increasing NO concentration,with the lowest rate dropping to about 50%. It can be seen that high temperature and high concentration of SO2 and NO are unfavorable for magnetic biochar mercury removal. In addition,the magneticbiochar deactivated by mercury removal has excellent thermal regeneration stability,with about 80% mercury removal efficiency after thermal regeneration at 450 °C and cycling four times.

张军峰(1980—),男,河北廊坊人,本科。E-mail:16260033@chnenergy.com.cn

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ZHANG Junfeng, WEI Shuzhou, SUN Daorong, et al. Mercury removal performance of magnetic biochar by acid gas during oxyfuel combustion atmosphere[J].Clean Coal Technology,2024,30(10):199−207.