BiFeO_3催化过一硫酸氢钾氧化脱除烟气中的单质汞

采用溶胶凝胶法制备了磁性催化剂铁酸铋(BiFeO_3).在小型的鼓泡反应器上,利用BiFeO_3催化活化过一硫酸氢钾(PMS),开展烟气中单质汞脱除实验研究,考察了催化剂用量、PMS浓度、初始溶液pH、反应温度,烟气组分对汞脱除效率的影响并得到了最优的实验条件.当BiFeO_3用量为0.5g/L,PMS浓度为5.2 mmol/L,溶液初始pH为8,反应温度为70℃时,反应周期100min内Hg~0的平均脱除效率可稳定达到80%.为推测反应机理,以甲醇和叔丁醇为淬灭剂,间接地证明了催化氧化脱汞反应过程中的活性物种为·SO_4~-和·OH,且·SO_4~-处于主导地位.借助于X射线衍射(XRD)、扫描电子显微镜(SEM)、比表面积(BET)、磁滞回线(VSM)测试分析了催化剂的特性,利用原子荧光光度计测定了脱汞产物,由此推测了脱汞反应机理.

Removal element mercury from flue gas using peroxymonosulfate solution catalyzed by BiFeO_3

BiFeO_3 magnetic catalyst was synthesized by the sol-gel method.The catalytic activity of BiFeO_3 was evaluated for the activated Peroxymonosulfate(PMS)for removal elemental mercury in flue gas at a self-design bubbling reactor.The effects of dosage of the catalyst,PMS concentration,solution pH,reaction temperature,and flue gas components on the removal of elemental mercury were investigated systematically,and the optimum conditions were obtained.The result indicated that the removal efficiency of elemental mercury was achieved 80% when PMS concentration was 5.2 mmol/L,dosage of the catalyst was 0.5 g/L,solution pH was 8 and the reaction temperature was 70℃.What's more,it was demonstrated indirectly that·SO_4~- and·OH were the active species when Hg~0 was oxidized to Hg~(2+),where tert-butyl alcohol and methyl alcohol were used as quenchers.BiFeO_3 catalyst was characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),BET method,and hysteresis loop(VSM).The removal of mercury product was determined by atomic fluorescence photometer.The removal mercury mechanism was speculated eventually.