Molecular simulation study on the anti-As2O3 poisoning ability of γ-Fe2O3
ZHOU Wen-bo1, NIU Sheng-li1, LIU Si-tong1, WANG Dong2, HAN Kui-hua1, WANG Yong-zheng1
1. Shandong Engineering Laboratory for High-efficiency Energy Conservation and Energy Storage Technology & Equipment, School of Energy and Power Engineering, Shandong University, Jinan 250061, China; 2. Brook Byers Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332, United States
Abstract:The γ-Fe2O3 catalyst, due to its advantages in low cost and high catalytic performance, is thought to be a promising medium-low temperature SCR catalyst, but the As2O3 in the flue gas likely becomes seriously deactivated. In this study, the density functional theory was used to characterize the adsorption of As2O3 on the γ-Fe2O3 surface as well as the mechanism of doping modification to improve the anti-As2O3 poisoning performance. The adsorption properties of As2O3 on the intact and O-deficient γ-Fe2O3(001) surfaces were examined, including adsorption site, adsorption structure, adsorption energy, PDOS, etc. At the same time, the catalyst model of γ-Fe2O3 doped with Mo, Ti, and Mg was established to understand the mechanism of doping additives on improving the resistance to arsenic poisoning. The results show that the As2O3 tends to be chemically adsorbed on Feoct sites on the γ-Fe2O3(001) surface with the O-terminus, and strong interaction and electron transfer occur during the adsorption process. When there are O defects on the surface, the adsorption energy of As2O3 molecules increases. Mo, Ti, and Mg tend to be doped in Feoct sites, which thus enhances the adsorption capacity of As2O3. Increasing the doping amount of Mo can promote the adsorption of As2O3. As2O3 tends to react with the more active Mo, Ti, and Mg, thereby protecting the active Fe sites from arsenic poisoning. The doping of Ti and Mg also inhibits the adsorption of As2O3 on adjacent Fe sites. The doping of Mo, Ti, and Mg also promotes the adsorption of NH3 on the catalyst surface and elevates the acidity of the surface, which is beneficial to the SCR reaction and to improving the anti-arsenic poisoning performance of the γ-Fe2O3 catalyst.
周文波, 牛胜利, 刘思彤, 王栋, 韩奎华, 王永征. γ-Fe2O3抗As2O3中毒能力的分子模拟[J]. 中国环境科学, 2022, 42(8): 3600-3609.
ZHOU Wen-bo, NIU Sheng-li, LIU Si-tong, WANG Dong, HAN Kui-hua, WANG Yong-zheng. Molecular simulation study on the anti-As2O3 poisoning ability of γ-Fe2O3. CHINA ENVIRONMENTAL SCIENCECE, 2022, 42(8): 3600-3609.
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