The effect of mechanical-chemical-brominated modification on physicochemical properties and mercury removal performance of coal-fired by-product
The effect of mechanical-chemical-brominated modification on physicochemical properties and mercury removal performance of coal-fired by-product
复制标题
机械化学溴化改性对燃煤副产品理化性质及脱汞性能的影响
DOI：
10.1016/j.fuel.2020.117041
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发表时间：
2020-04-15
期刊：
影响因子：
7.4
通讯作者：
Liu, Meng
中科院分区：
文献类型：
--
作者：
Geng, Xinze;Hu, Jiwei;Liu, Meng
燃煤是我国最大的人为汞排放源之一，燃煤副产物粉煤灰和底灰是制备低成本、高效、可循环利用的脱汞吸附剂的原料。采用全方位行星式球磨机制备了机械化学溴化FA（FA-MC-Br）和BA（BA-MC-Br）。通过X射线光电子能谱（XPS）、Brunauer-Emmet-Teller、扫描电镜（SEM）和汞程序升温脱附等分析手段，对FA、FA-MC-Br、BA和BA-MC-Br的理化性质进行了比较和讨论。采用固定床反应系统对4种样品的除汞能力进行了评价，结果表明，机械-化学-溴化改性对FA和BA的孔结构无明显影响，但使其粒径明显减小，表面无定形相增多。此外，BA表面的Fe含量也有所增加。FA-MC-Br和BA-MC-Br的载溴率分别为61.35%和48.67%。机械-化学-溴化改性可显著提高FA/BA的除汞能力。FA-MC-Br和BA-MC-Br去除Hg-0的反应机理和途径可归纳为以下两部分：（a）HgO被样品表面活性化学吸附氧和Fe ~（3+）吸附氧化; (b)HgBr 2是由C-Br和Hg-0之间的反应生成的，其遵循Eley-Rideal机理。
Coal combustion is one of the largest anthropogenic mercury emission source in China, while the coal-fired by-product such as fly ash (FA) and bottom ash (BA) are raw material for making mercury removal adsorbent with low-cost and high efficient and recycling. The mechanical-chemical brominated FA (FA-MC-Br) and BA (BA-MC-Br) were prepared through the omni-directional planetary ball mill. The physicochemical properties of FA, FA-MC-Br, BA, and BA-MC-Br were compared and discussed based on analyses of the X-ray photoelectron spectroscopy, Brunauer-Emmet-Teller, Scanning Electron Microscopy, and mercury temperature programmed desorption, etc. The mercury-removal ability of the four samples was estimated by fixed-bed react system which showed that the mechanical-chemical-brominated modification has no significant effect on the pore structures of FA and BA but obviously reducing their particle sizes and increase the amorphous phase on surface of FA and BA. Besides, the Fe content on the surface of BA was enhanced as well. The Br loading rate of FA-MC-Br and BA-MC-Br is 61.35% and 48.67%, respectively. The mercury removal ability of FA/BA can be significantly improved by the mechanical-chemical-brominated modification. The reaction mechanism and pathways of Hg-0 removal by FA-MC-Br and BA-MC-Br can be deduced as the following two parts: (a) HgO is adsorbed and oxidized by the active chemisorbed oxygen and Fe3+ on the surface of samples. (b) HgBr2 is generated by the reaction between the C-Br and Hg-0, which follows the Eley-Rideal mechanism.