Mn/Ce掺杂改性半焦对模拟煤气中单质汞的脱除性能研究  

Removal of vapor-phase elemental mercury from simulated syngas using semi-coke modified by Mn/Ce doping

作　　者：张华伟[1] 陈江艳[1] 赵可[1] 牛庆欣 王力[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：《燃料化学学报》2016年第4期394-400,共7页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(51406107;21276146);山东科技大学研究生科技创新基金(YC150110)项目资助~~

摘　　要：制备了Mn改性半焦(Mn-SC)及Mn/Ce掺杂改性半焦(Mn/Ce-SC)吸附剂,在小型固定床吸附反应器上考查了改性半焦对模拟煤气中单质汞的吸附特性,并利用BET比表面积测试、X射线衍射、X射线光电子能谱等手段对半焦吸附剂进行了表征。结果表明,Mn改性后半焦的比表面积、总孔容和平均孔径都有所增加,而Mn/Ce掺杂改性半焦的孔隙结构发达程度有一定程度的降低;Mn_xO_y及Ce_xO_y均以高分散的无定形态存在于半焦表面;Mn/Ce-SC的脱汞效率明显高于Mn-SC和SC,其脱汞性能随吸附温度的升高会有所下降,但总体保持较高的水平。当煤气中有1%的O_2存在时,Mn/Ce-SC表面会发生Ce^(4+)/Ce^(3+)间的氧化还原反应循环,从而将煤气中的气相氧转化为高氧化活性的晶格氧,使Mn/Ce-SC的脱汞效率一直稳定在95%以上,Hg0在Mn/Ce-SC半焦表面的吸附符合Mars-Maessen机制。The Mn-SC and Mn / Ce-SC adsorbents were prepared by modification of semi-coke（ SC） with manganese nitrate and cerium nitrate, and their mercury removal performance in simulated syngas was investigated in a lab-scale fix-bed reactor. Effect of cerium and manganese on the surface physical and chemical properties of semi-coke was characterized by Brunauer-Emmett-Teller（ BET）,X-ray diffraction（ XRD）,and X-ray photoelectron spectroscopy（ XPS）. The results showthat BET surface area,average pore size and total pore volume of Mn-SC are higher than those of SC,while Mn / Ce doping modification has adverse effect on the pore structure; Mn_xO_y and Ce_xO_y exist in highly dispersive amorphous form on the surface of semi-coke. The mercury removal efficiency of Mn / Ce-SC is higher than that of Mn-SC and SC,and decreases with increase in adsorption temperature. Generally, the Mn / Ce-SC exhibits good mercury removal performance at elevated temperatures. With the presence of 1% of O2,oxidation and reduction reaction cycle could occur on the surface of Mn / Ce-SC,and oxygen in syngas is converted into lattice oxygen with high oxidation activity. Based on the Mars-Maessen mechanism,Hg0 could be oxidized to Hg2＋by lattice oxygen and then adsorbed. The mercury removal efficiency of Mn / Ce-SC maintains over 95% at 260 ℃.

关 键 词：Mn/Ce掺杂 改性半焦 脱汞机理 煤气 

分 类 号：TQ534.9[化学工程—煤化学工程]