改性褐煤半焦的表面性质及对气态Hg^0的吸附特性  

Study on Surface Properties and Adsorption Performance of Modified Semi-Coke for Gas-Phase Hg^0

作　　者：王力[1] 陈继涛[1] 张华伟[1] 张林林[1] 刘秀丽[1] 

机构地区：[1]山东科技大学化学与环境工程学院,山东青岛266590

出　　处：《环境科学研究》2014年第8期820-826,共7页Research of Environmental Sciences

基　　金：国家自然科学基金项目(21276146)

摘　　要：以廉价的褐煤为原料制备褐煤原料半焦,通过化学改性研制脱除烟气中气态Hg0的改性半焦(MnOx褐煤半焦)吸附剂,运用N2吸附-脱附、SEM(扫描电镜)、XRD(X射线衍射仪)及XPS(X射线光电子能谱)等对吸附剂的表面特性进行表征与分析,利用固定床吸附试验考察2种吸附剂对气态Hg0的吸附特性.结果表明:原料半焦与改性半焦均具有较发达的孔隙结构,并且以2~5 nm的介孔结构为主;经化学改性后,半焦表面石墨化程度有所提高,石墨碳C─C所占比例由51.37%增至76.17%;MnOx主要以高度分散的无定形状态均匀分布于改性半焦表面.固定床吸附试验结果表明,温度为140℃时,原料半焦对气态Hg0的吸附性能较差,而改性半焦则表现良好,其最高吸附效率可达85.6%;初始ρ(Hg0)分别为10.1、20.3、30.0、40.6μgm3时,改性半焦的吸附性能随初始ρ(Hg0)升高而增强;当吸附温度由30℃升至140℃时,改性半焦的吸附性能也随着吸附温度的升高而增强.改性半焦对气态Hg0的吸附作用应主要为化学吸附,被吸附后的汞主要以氧化态(Hg2+)形式存在.To develop a novel adsorbent for the removal of gas-phase Hg0 from flue gas,MnOx/semi-coke was prepared with low-cost lignite by a chemical method,and its surface properties were characterized with N2adsorption-desorption,scanning electronic microscopy（ SEM）,X-ray diffraction（ XRD） and X-ray photoelectron spectroscopy（ XPS）. The adsorption performance of the adsorbent for gasphase Hg0 was investigated with a fixed-bed reactor system. Characterization tests suggest that both the lignite semi-coke and the modified sample possessed a rich pore structure,mainly in the form of micropores from 2 to 5 nm. Compared to raw semi-coke,the content of graphitic carbon on the surface of the modified semi-coke was improved greatly from 51. 37% to 76. 17%. MnOxwas evenly distributed on the surface of the modified semi-coke in a highly dispersed amorphous state. Hg0 adsorption experiment indicated that the modified semicoke had excellent adsorption performance for gas-phase Hg0 at 140 ℃ to 85. 6%,whereas the raw semi-coke only showed a weak adsorption performance. The adsorption performance of the modified semi-coke improved as Hg0 inlet concentration increased when tested at levels of 10. 1,20. 3,30. 0 and 40. 6 μg/m3. The same trend was observed when adsorption temperature increased from 30 ℃ to 140℃. Chemisorption played a key a role in the adsorption process,and mercury on the surface of the modified semi-coke mainly existed in the oxidation state（ Hg2 ＋）.

关 键 词：褐煤半焦 MNOX 气态Hg0 燃煤烟气脱汞 吸附性能 

分 类 号：X513[环境科学与工程—环境工程]