Adsorption and reaction mechanism, of arsenic vapors over γ-Al2O3 in the simulated flue gas containing acid gases
Adsorption and reaction mechanism, of arsenic vapors over γ-Al2O3 in the simulated flue gas containing acid gases
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DOI：
10.1016/j.chemosphere.2017.03.114
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发表时间：
2017-08-01
期刊：
影响因子：
8.8
通讯作者：
Yao, Hong
中科院分区：
文献类型：
--
作者：
Hu, Hongyun;Chen, Dunkui;Yao, Hong
燃料燃烧和金属冶炼烟气中的砷排放造成严重的污染。添加吸附剂是一种很有前途的高温烟气砷捕集方法。然而，由于吸附剂与砷和这些酸性气体的竞争反应，从富含SO2/HCl的烟气中去除砷是困难的。针对这一问题，本文研究了γ-Al_2O_3对砷的吸附机理、抗酸性气体性能以及再生性能。结果表明，γ-Al 2 O3具有良好的抗酸性气体性能，在573 ~ 1023 K的较宽温度范围内，γ-Al 2 O3对砷的吸附效果较好。高温吸附（如1173 K）导致γ-Al 2 O3的比表面积减小，晶体结构发生重排，砷吸附活性位减少。砷的吸附被证实发生在不同的活性位点的γ-Al_2O_3形成各种吸附物种。提高温度有利于砷转化为更稳定的化学吸附的As 3+和As 5+，难以通过热处理再生去除。幸运的是，用NaOH溶液可以很好地再生废γ-Al_2O_3。(C)2017爱思唯尔有限公司版权所有
Arsenic emission from fuel combustion and metal smelting flue gas causes serious pollution. Addition of sorbents is a promising way for the arsenic capture from high temperature flue gas. However, it is difficult to remove arsenic from SO2/HCl-rich flue gas due to the competitive reaction of the sorbents with arsenic and these acid gases. To solve this problem, arsenic adsorption over gamma-Al2O3 was studied in this work to evaluate its adsorption mechanism, resistance to acid gases as well as regeneration behavior. The results show that gamma-Al2O3 had good resistance to acid gases and the arsenic adsorption by gamma-Al2O3 could be effectively carried out at a wide temperature range between 573 and 1023 K. Nevertheless, adsorption at higher-temperature (like 1173 K) leaded to the decrease of surface area and the rearrangement of crystal structure of gamma-Al2O3, reducing the active sites for arsenic adsorption. The adsorption of arsenic was confirmed to occur at different active sites in gamma-Al2O3 by forming various adsorbed species. Increasing temperature facilitated arsenic transformation into more stable chemisorbed As3+ and As5+ which were difficult to remove through thermal treatment regeneration. Fortunately, the regeneration of spent gamma-Al2O3 could be well performed using NaOH solution. (C) 2017 Elsevier Ltd. All rights reserved.