Mo/Fe<sub>3</sub>O<sub>4</sub>(111)表面对燃煤烟气汞吸附的密度泛函研究

陈佳敏; 周长松; 杨宏旻; 吴昊

Mo/Fe₃O₄(111)表面对燃煤烟气汞吸附的密度泛函研究

南京师范大学能源与机械工程学院, 江苏南京 210042

基金项目:

国家自然科学基金 51676101

国家自然科学基金 51806107

江苏省自然科学基金项目 BK20161558

江苏省自然科学基金项目 BK20180731

详细信息

中图分类号: X701
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出版历程
- 收稿日期: 2020-01-19
- 修回日期: 2020-03-16
- 网络出版日期: 2021-01-23
- 刊出日期: 2020-05-10

A DFT study on the adsorption of various mercury species in the coal combustion flue gases on the Mo-doped Fe₃O₄(111) surface

School of Energy&Mechanical Engineering, Nanjing Normal University, Nanjing 210042, China

Funds:

the National Natural Science Foundation of China 51676101

the National Natural Science Foundation of China 51806107

the Natural Science Foundation of Jiangsu Province BK20161558

the Natural Science Foundation of Jiangsu Province BK20180731

More Information

Corresponding author: ZHOU Chang-song, E-mail:cszhou@njnu.edu.cn

摘要

摘要: 利用CASTEP软件包采用密度泛函理论计算研究了过渡金属Mo掺杂Fe₃O₄（111）Fe_tet表面对Hg⁰、HgCl和HgCl₂的吸附特征，分析了Mo掺杂前后Fe₃O₄（111）Fe_tet表面上不同汞物种的吸附形态。结果表明，Mo掺杂Fe₃O₄（111）Fe_tet表面对HgCl和HgCl₂为化学吸附，而对Hg⁰的吸附为物理吸附；与纯净表面相比，HgCl在Mo原子掺杂表面上的吸附能提高了40%-66%。HgCl₂在纯净Fe₃O₄（111）Fe_tet表面形成"M"形结构；而掺杂Mo原子后，由于Cl原子与Mo原子之间更强的相互作用，使得HgCl₂发生了完全解离，两个Cl原子分别与Mo原子和Fe原子成键吸附在表面，Hg脱附。相关研究结果可为脱除燃煤烟气中的汞提供一定的理论指导。
- 汞 /
- 密度泛函理论 /
- Mo掺杂 /
- Fe₃O₄(111)表面 /
- 吸附
Abstract: The adsorption characteristics of Hg⁰, HgCl and HgCl₂ on the Mo-doped Fe₃O₄ (111) Fe_tet surface were investigated by density functional theory (DFT) calculation with the CASTEP software package. The results indicate that both HgCl and HgCl₂ are chemically adsorbed on the Mo-doped Fe₃O₄ (111) Fe_tet surface, whereas Hg⁰ is bound to the surface by physisorption. The binding energies of HgCl on the Mo-doped Fe₃O₄ (111) Fe_tet surface is about 40%-66% higher than that on the pure Fe₃O₄ (111) Fe_tet surface. For the adsorption of HgCl₂ molecule on the pure Fe₃O₄ (111) Fe_tet surface, two Cl atoms interact with one Mo atom and one Fe atom, forming the "M" structure; in contrast, on the Mo-doped Fe₃O₄ (111) Fe_tet surface, the stronger interaction between Cl atom and Mo atom allows a complete dissociation of HgCl₂ and release of Hg. The adsorption mechanism of mercury species on the Mo-doped Fe₃O₄ (111) Fe_tet surface revealed in this work may be helpful for the practical removal of mercury from coal-fired flue gases.
- mercury /
- density functional theory /
- Mo doped /
- Fe₃O₄(111) surface /
- adsorption

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图 1 Mo/Fe₃O₄(111)Fe_tet结构图

Figure 1 Structure of Mo-doped Fe₃O₄(111) surface with Fe_tet termination

(a): side view; (b): front view(red: O atom; purple: Fe atom; green: Mo atom)

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图 2 Hg⁰在Fe₃O₄(111)和Mo/Fe₃O₄(111)表面的稳定吸附构型

Figure 2 Stable configurations of Hg⁰ on the Fe₃O₄(111) and Mo/Fe₃O₄(111) surfaces

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图 3 HgCl在p(1×1) Fe₃O₄(111)和Mo/Fe₃O₄(111)表面的稳定吸附构型

Figure 3 Stable configurations of HgCl on the p(1×1) Fe₃O₄(111)Fe_tet and Mo/Fe₃O₄(111)Fe_tet surfaces

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图 4 HgCl在p(2×1) Fe₃O₄(111) Fe_tet和Mo/Fe₃O₄(111)Fe_tet面的稳定吸附构型

Figure 4 Stable configurations of HgCl on the p(2×1) Fe₃O₄(111)Fe_tet and Mo/Fe₃O₄(111)Fe_tet surfaces

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图 5 3A构型中PDOS图

Figure 5 PDOS of the configuration 3A

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图 6 HgCl₂在p(2×1) Fe₃O₄(111)和Mo/Fe₃O₄(111)面的稳定吸附构型

Figure 6 Stable configurations of HgCl₂ on the p(2×1) Fe₃O₄(111) and Mo/Fe₃O₄(111) surfaces

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表 1 Hg⁰在Fe₃O₄(111)和Mo/Fe₃O₄(111)表面的稳定构型参数

Table 1 Optimized parameters for Hg⁰ on theFe₃O₄(111) and Mo/Fe₃O₄(111) surfaces

		Adsorption side	E_ads/(kJ·mol^-1)	R_Hg-X/nm	Q_Hg/e
1×1	A	Fe Top	-38.10	0.278	0.19
	B	Mo Top	-33.64	0.298	0.11
2×1	C	Mo Top	-27.34	0.296	0.16
	D	Fe Top	-29.58	0.279	0.20
E_ads denotes adsorption energies, R_Hg-Mo and R_Hg-Fe denote distances between adsorbed Hg and Mo/Fe, respectively, Q_Hg denotes Mulliken charge of Hg atoms

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表 2 HgCl在p(1×1) Fe₃O₄(111)和Mo/Fe₃O₄(111)表面的稳定构型参数

Table 2 Optimized parameters for HgCl on the p(1×1) Fe₃O₄(111) and Mo/Fe₃O₄(111) surfaces

		E_ads/(kJ·mol^-1)	R_Cl-X/R_Hg-X/nm	R_Hg-Cl/nm	Q_Hg/e	Q_Cl/e
Fe₃O₄(111) Fe_tet	1A	-135.18	-/0.255	0.235	0.37	-0.31
	1B	-214.21	0.224/-	0.353	0.12	-0.30
	1C	-137.22	-/0.208	0.228	0.70	-0.27
Mo/Fe₃O₄(111) Fe_tet	1D	-224.47	-/0.268	0.234	0.30	-0.33
	1E	-332.78	0.224/-	0.384	0.02	-0.21
	1F	-93.82	-/0.210	0.230	0.59	-0.26

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表 3 HgCl在p(2×1) Fe₃O₄(111) Fe_tet和Mo/Fe₃O₄(111)表面的稳定构型参数

Table 3 Optimized parameters for HgCl on the p(2×1) Fe₃O₄(111) and Mo/Fe₃O₄(111) surfaces

		E_ads/(kJ·mol^-1)	R_Cl-X/R_Hg-X/nm	R_Hg-Cl/nm	Q_Hg/e	Q_Cl/e
Fe₃O₄(111) Fe_tet	2A	-265.59	0.215/0.273	0.500	0.28	-0.36
	2B	-211.21	0.214/-	0.334	0.07	-0.31
	2C	-137.90	-/0.255	0.236	0.39	-0.32
	2D	-141.63	-/0.208	0.228	0.70	-0.28
Mo/Fe₃O₄(111) Fe_tet	3A	-371.56	0.226/0.273	0.600	0.23	-0.26
	3B	-340.62	0.225/-	0.402	0.04	-0.22
	3C	-257.23	0.297/0.215	0.420	0.26	-0.37
	3D	-337.09	0.224/-	0.353	0.01	-0.21
	3E	-213.25	-/0.214	0.368	0.02	-0.33
	3F	-229.42	-/0.268	0.234	0.34	-0.35
	3G	-130.29	-/0.255	0.237	0.32	-0.34
	3H	-118.30	-/0.208	0.230	0.66	-0.28
	3I	-111.35	-/0.209	0.229	0.63	-0.27

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表 4 HgCl₂在p(2×1) Fe₃O₄(111)和Mo/Fe₃O₄(111)表面的稳定构型参数

Table 4 Optimized parameters for HgCl₂ on the p(2×1) Fe₃O₄(111)Fe_tet and Mo/Fe₃O₄(111)Fe_tet surfaces (2×1 surface cell)

		E_ads/(kJ·mol^-1)	R_{Cl₁-X/Cl₂-X/Hg-X}/nm	R_Hg-Cl₁/R_Hg-Cl₂/nm	Angle/(°)	Q_Hg/e	Q_Cl₁/Q_Cl₂/e
Fe₃O₄(111) Fe_tet	4A	-165.81	0.231/0.233/-	0.254/0.249	137.68	0.73	-0.30/-0.30
	4B	-32.86	0.233/-	0.229/0.236	178.68	0.74	-0.29/-0.37
Mo/Fe₃O₄(111) Fe_tet	4C	-290.18	0.214/0.223/-	0.345/0.366	124.36	0.04	-0.31/-0.17
	4D	-6.55	-/-/0.293	0.233/0.232	174.07	0.60	-0.35/-0.35
	4E	-85.71	-/0.227/-	0.241/0.307	179.70	0.35	-0.29/-0.25
	4F	-22.30	-/0.237/-	0.232/0.242	179.29	0.66	-0.29/-0.38

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