Crucial factors controlling the formation of halogenated organic compounds during high-temperature combustion proc esse s

采用XRD、SEM-EPMA、XPS和TPD等技术对6个炼钢电弧炉布袋除尘器粉尘和6个燃煤电厂电除尘器飞灰样品进行了表征，分别考察了炼钢和燃煤过程中控制有机卤素化合物生成的几个因素。粉尘样品含2. 1-6. 4wt%干重的碳元素，部分碳元素在TPD中可释放CO_2，提供碳活性中心。其数量与粉尘中六氯苯的浓度密切相关。结果表明，样品中的Zn主要由ZnFe_2O_4、ZnO和表面ZnCO_3组成，ZnCO_3含量越高，样品中的六氯苯浓度越高。另一方面，灰分包括20-130 μ g/g-干和0. 5-4. 2wt%-干的F和C元素，分别，这些成分富集在灰表面的最外层。F由无机和有机官能团组成，后者的比例高达84- 93mol%。C表面含有羧基、内酯/酸酐和酚基等不同类型的氧物种，这些氧物种在800℃以上大部分分解为CO2或CO，形成碳活性中心。当O-官能形式的量增加时，有机CF形式的含量趋于几乎线性增加。

Six dust samples recovered from bag filters of electric arc furnaces for steelmaking or six fly ashes recovered from electrostatic precipitators in pulverized coal-fired power plants are characterized by use of XRD, SEM-EPMA, XPS and TPD techniques to examine several factors controlling the formation of organic halogen compounds in the steelmaking or coal combustion process, respectively. The dust samples contain 2. 1-6. 4 wt%-dry of carbon element, and some of the C can release CO_2 in the TPD up to 300℃to provide carbon active sites. The number is related closely to hexachlorobenzene(HCB) concentration of each dust. Further, it is suggested that the Zn present in the samples consists of ZnFe_2O_4, ZnO and surface ZnCO_3, and the dust with a larger content of the ZnCO_3 has a higher concentration of HCB. On the other hand, the ashes include 20-130цg/gg-dry and 0. 5-4. 2 wt%-dry of F and C elements, respectively, and these components are enriched at the outermost layer of the ash surface. The F consists of both inorganic and organic functionalities, and the proportion of the latter is as high as 84-93 mol%. The C has different types of surface oxygen species, such as carboxyl, lactone/acid anhydride and phenolic groups, and most of these groups decompose into CO_2 or CO up to 800℃to give carbon active sites. When the amount of the O-functional forms increases, the content of organic CF forms tends to increase almost linearly.