论文总字数：24031字

摘 要

众所周知，氮氧化物对生态环境和人体健康都造成了极大的威胁，是很常见的大气污染物。截至目前为止人们发现国际上应用最广泛的烟气脱硝技术是低温NH₃-SCR技术。该技术具有低能耗、低毒化和低成本等优点，核心是催化剂。研发者将NH₃-SCR装置布置在除尘和脱硫装置之后，发现此时需要一种具有低温高活性的催化剂，因此，锰基催化剂被广泛研究。

本文首先以硝酸锰，钛酸四丁酯为前驱体，采用自发沉积策略成功制备出一系列不同锰含量的Mn_aTi_1-a催化剂，通过XRD、Raman、SEM、TEM、N₂吸附-脱附、XPS、H₂-TPR、NH₃-TPD及原位FTIR等表征技术对催化剂进行了分析。结果表明，这一系列催化剂具有完全非晶态结构，Mn、Ti之间存在强相互作用，促进形成高度融结态，具有较大比表面积和孔容。其中Mn_0.5Ti_0.5具有较强的表面酸性和较多的L酸量，较高浓度的表面Mn⁴ 离子，较强的氧化还原能力，所以表现出了更优异的脱硝活性。在结合表征结果的基础上推导出Mn_aTi_1-a催化剂合理的反应机理过程。

关键词：氮氧化物 Mn_aTi_1-a催化剂 反应机理

Abstract

As we all know, nitrogen oxides have caused a great threat on the ecological environment and human health , they are very common air pollutants. So far it has been found that the most widely used flue gas denitrification technology is low temperature NH₃-SCR technology. The technology has the advantages of low energy consumption, low toxicity and low cost, the core of this process is the catalyst. it is found that a catalyst with high activity at the low temperature is required at this time, and therefore, the manganese-based catalyst is widely studied.

In this paper, manganese nitrate and tetrabutyl titanate are used as precursors and a series of Mn_aTi_1-a catalysts with varying Mn contents are prepared by a spontaneous deposition method. The structure and properties of the catalysts are studied by the means of XRD、Raman、SEM、TEM、N₂ adsorption-desorption、XPS、H₂-TPR、NH₃-TPD and In-situ FTIR. The results show that the series of catalysts have a complete amorphous structure, a strong interaction between Mn and Ti, a large specific surface area and pore volume, which promote to form a high inosculated state. Among them, The Mn_0.5Ti_0.5 has strong surface acidity and L acid content, and the higher concentration of Mn⁴ ions on the surface has stronger redox ability, and thus exhibits more excellent NH₃-SCR activity. Mechanism of NH₃-SCR reaction over Mn_0.5Ti_0.5 catalyst is proposed based on the physico-chemical properties and In-situ FTIR results.

Key words: nitrogen oxide; Mn_aTi_1-a catalysts; Mechanism

目录

摘 要 I

Abstract II

第一章 文献综述 1

1.1 课题背景 1

1.2 NO_x的脱除及控制技术研究现状 1

1.3 SCR技术研究现状 2

1.3.1 SCR工艺研究 2

1.3.2 锰基催化剂研究 3

1.4 NH₃-SCR的反应过程和机理研究 4

1.5 课题的意义、思路和内容 5

1.5.1 课题的意义 5

1.5.2 研究内容 5

第二章 实验部分 7

2.1 实验仪器及原料 7

2.1.1 实验主要仪器 7

2.1.2 实验试剂及气体 7

2.2 催化剂的制备 8

2.3 催化剂的表征 8

2.3.1 X射线荧光光谱(XRF) 8

2.3.2 X-射线衍射(XRD) 9

2.3.3 拉曼光谱(Raman) 9

2.3.4 N₂吸附-脱附测试 9

2.3.5 环境扫描电镜(SEM) 9

2.3.6 透射电子显微镜(TEM) 9

2.3.7 H₂程序升温还原(H₂-TPR) 9

2.3.8 NH₃程序升温脱附(NH₃-TPD) 9

2.3.9 电子能谱(XPS) 10

2.3.10 原位红外光谱(In-situ FTIR) 10

2.4 催化剂脱硝性能评价 10

2.4.1 脱硝性能评价装置 10

2.4.2 脱硝性能评价试验 11

第三章 NH₃-SCR过程机制的研究 12

3.1. 催化活性结果 12

3.1.1 NH₃-SCR活性结果 12

3.1.2 H₂O/SO₂对NH₃-SCR反应的影响 13

3.2 表征 14

3.2.1 XRD和Raman分析 14

3.2.2 SEM和TEM分析 15

3.2.3 N₂吸附-脱附分析 15

3.2.4 XPS分析 16

3.2.5 H₂-TPR和NH₃-TPD分析 18

3.3 原位FTIR分析 19

3.3.1 NH₃/NO O₂吸附 19

3.3.2 NO O₂和NH₃物种在Mn_0.5Ti_0.5催化剂表面的瞬态反应 20

3.3.3 NO O₂和NH₃共同通入 21

3.3.4 原位FTIR分析的过程机制 22

第四章 总结 23

参考文献 24

致谢 27

1. 文献综述

1.1 课题背景

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