多壁碳纳米管负载FeS2的制备及脱汞性能分析

Preparation and demercuration analysis of multi-walled carbon nanotubes supported FeS

采用硝酸铁与硫脲在溶剂热反应条件下制备FeS2,利用物理浸渍法将FeS2负载至多壁碳纳米管(MWCNTs)上,借助扫描电镜(SEM)、X射线衍射(XRD)、X光电子能谱(XPS)等分析测试手段对制备样品的结构特性进行探究,通过固定床反应器研究模拟烟气氛围下吸附剂对烟气中单质汞的吸附特性。实验考察了不同FeS2负载量、烟气初始汞浓度、床层温度以及O2、NO和SO2对吸附剂脱汞效率的影响。结果表明,制备出的FeS2分散性较好,呈球状晶体,表面均匀覆盖着MWCNTs,成团簇状。当负载量为10%、反应温度为70℃时,FeS2/MWCNTs的吸附效果最好,最高脱除效率能达到100%,60min后脱除效率仍有80.3%。TPD脱附曲线和XPS分析结果进一步表明烟气中的Hg0被氧化成Hg2+以HgS的形式附着在吸附剂表面,证实吸附剂以化学吸附为主。此外,汞脱除效率随初始汞浓度的增加而降低,汞吸附容量却随之增加,60min最高能达到5.1μg/g。酸性气体NO和SO2的存在,占据了吸附剂表面的活性点位,不利于Hg0的吸附,但低浓度NO对吸附剂的整体效果影响不大,抗NO性能较好。

Ferric nitrate and thiourea were used to prepare FeS2 under solvothermal reaction conditions which were loaded onto MWCNTs(multi-walled carbon nanotubes) by physical impregnation method. The structural characteristics of the prepared samples were investigated by means of analytical methods such as SEM, XRD and XPS. The adsorption characteristics of the adsorbent on the elemental mercury in the flue gas under simulated flue gas atmosphere were studied by a fixed bed reactor. The effects of different FeS2 loading, initial mercury concentration, reaction temperature and O2, NO and SO2 on the mercury removal efficiency of the adsorbent were investigated. The results showed that the prepared FeS2 had good dispersibility and was spherical crystal. The surface was evenly covered with MWCNTs and clustered.When the loading was 10% and the reaction temperature was 70℃, the adsorption effect of FeS2/MWCNTs was the best, the highest removal efficiency could reach 100%, and the removal efficiency was 80.3% after 60 min. The TPD desorption curve and XPS analysis results further indicated that Hg0 in the flue gas was oxidized to Hg2+ and was attached to the surface of the adsorbent in the form of HgS, confirming that the adsorbent was mainly chemisorbed. In addition, the mercury removal efficiency decreased with the increase of the initial mercury concentration, but the mercury adsorption capacity increased, and the highest could reach 5.1μg/g in 60 min. The presence of NO and SO2 occupied the active site on the surface of the adsorbent, which was not conducive to the adsorption of Hg0, but the low concentration of NO had little effect on the overall effect of the adsorbent, and the anti-NO performance of adsorbent was better.