吸附
砷
化学吸附
密度泛函理论
化学
吸附剂
烟气
无机化学
分子
计算化学
物理化学
有机化学
出处
期刊:Energy & Fuels
[American Chemical Society]
日期:2019-01-09
卷期号:33 (2): 1414-1421
被引量:52
标识
DOI:10.1021/acs.energyfuels.8b04155
摘要
Iron-based sorbent addition is a promising method for arsenic removal from coal-fired flue gas, but the adsorption process and surface active site that are responsible for arsenic adsorption remain unclear. In this work, quantum chemistry methods based on the density functional theory are carried out to explore the mechanism of As2O3 adsorption on the Fe2O3 (001) surface. The results indicate that O-top and O-hollow sites served as the active sites for As2O3 adsorption on the α-Fe2O3 (001) surface; among these, the activity of the O-top is higher. The critical step of As2O3 adsorption lies in the bond breaking of the As–O bond in As2O3 molecule, which is confirmed by comparing binding energies of different adsorption sites. The previous experimental studies have proven that O2 and SO2 have a significant impact on arsenic adsorption, and herein, deep insights into arsenic adsorption in the presence of the above gas components are also included. Under the influence of oxygen, the conversion of the original Fe-top site into the O site results in chemisorption between arsenic and the α-Fe2O3 (001) surface, which is the primary cause for the promoting action of O2. In the presence of SO2, the adsorption activity of the original Fe-top site is enhanced by the newly formed Sads-top site. In addition, the As adsorption capacity of the original O-top site had also been promoted because of the SO2 adsorption.
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