摘 要

在改革开放以来的几十年里，我国经济发展愈发迅速，发展经济所消耗的能源量也随之越来越大。在我国能源使用比例中，煤炭仍然占据着绝对的主导作用。对于煤炭燃烧危害最大的污染物NO_x，占着氮氧化物总量95%的NO的脱除便成为了减轻氮氧化物污染、改善我国大气环境的关键。目前脱除NO_x应用较广、比较成熟、高效的技术之一即是选择性催化还原技术（SCR）。在SCR烟气脱硝系统中，最关键的部分之一即为选择何种的催化剂可以使催化剂的活性、寿命、抗中毒性得到最大程度的提高，同时催化剂的选择也是影响SCR系统脱硝成本最关键的一环。但是就我国工厂现在的条件，烟气中仍不可避免地存在部分SO₂残留，使得催化剂的活性物质与SO₂发生一系列反应，导致催化剂严重失活，无法继续脱硝。因此，寻找合适的提高催化剂抗硫性能的方法已成为低温SCR技术得以工业化、规模化、产业化的关键，成为近年来的研究热点。

本文以溶胶-凝胶法制备的MnO_x/TiO₂粉末催化剂为主要研究对象，首先考察了过渡金属Fe的掺入对催化剂综合性能的影响，筛选出了Fe的最佳掺入量，其中Fe/Ti为0.036的Fe-MnO_x/TiO₂催化剂提升脱硝性能最为明显。

其次研究了MnO_x/TiO₂的硫中毒实验，借助XRD、TG、H₂-TPR、BET等表征方法对中毒前后的MnO_x/TiO₂催化剂的物相、热稳定性、比表面积、样品氧化还原性能等进行分析。结果表明：SO₂会极大地抑制锰钛催化剂的氧化还原能力，在SO₂环境下，SCR-催化反应中会生成铵盐和锰硫酸盐，它们会附着在催化剂表面和孔结构中，使催化剂比表面积大幅度下降，活性组分减少，从而使催化剂脱硝性能减弱。

最后通过Fe的引入来提升MnO_x/TiO₂催化剂的抗硫性能，研究发现其中Fe/Ti为0.036的Fe-MnO_x/TiO₂催化剂抗SO₂性能最佳，在SO₂环境中，Fe的加入能抑制硫酸铵盐和硫酸盐等物质在催化剂表面的沉积，减少比表面积的损失。

关键词：SCR；MnO_x/TiO₂催化剂；Fe掺杂；抗硫性

Abstract

In the decades since the reform and opening up, China's economic development has become more and more rapid, and the energy consumed by the development of the economy is also growing. In the proportion of energy use in China, coal still occupies an absolute leading role. NO_x, which is the most harmful pollutant in coal combustion, is NO, which accounts for 95% of total nitrogen oxides. It is the key to reduce nitrogen oxide pollution and improve the atmospheric environment in China. At present, it is one of the widely used, more mature and efficient technologies to remove NO_x, which is the selective catalytic reduction technology (SCR). In SCR Flue Gas Removal denitrification system, one of the most critical part is the choice of catalyst which can make the catalyst activity, life time, anti poisoning is improved to the greatest extent. At the same time, catalyst selection and affecting the SCR system off NO_x cost is the key link. But conditions in factories in our country now, smoke still inevitably exist part of SO₂ residue, making catalyst active substances of SO₂ and a series of reactions, cause serious deactivation of the catalyst, can not continue to denitrification. Therefore, it has become the key to industrialization, scale and industrialization of low temperature SCR technology to find a suitable method to improve the sulfur resistance of the catalyst, which has become a hot research topic in recent years.

In this paper, a series of MnO_x/TiO₂ powder catalysts were prepared by sol-get method, as the main research objects. First of all, I did researches on the effects of doped transition metal Fe on the overall performance of the the MnO_x/TiO₂ catalyst, finding out the optimal Fe-MnO_x/TiO₂ that can enhance denitrification performance most obviously was the Fe-MnO_x/TiO₂ whose Fe/Ti was 0.036.

Furthermore, this paper studies the MnO_x/TiO₂ sulfur poisoning experiment and analyzed the catalysts’ phases, thermal stability, specific area and the redox property by means of XRD, TG, TPR and Bet characterization methods before and after the poisoning of MnO_x/TiO₂ catalyst material phase. The results are as follows: SO₂ can be greatly suppressed the redox ability of the MnO_x/TiO₂ catalysts.Under the environment of SO₂, the SCR reaction will generate ammonium and manganese sulfate and they will attach to the catalysts’ surface area and pore structure, whichdecreased the area surface greatly.The active component is reduced as well so that the NO conversion of the catalysts decreased.

Moreover, by means of the introduction of Fe, it was found to be beneficial to enhance the tolerance to sulfur of Mn-based catalysts, especially when the molar ratio of Fe to Ti was 0.036. By analyzing the experimentation, we can draw a conclusion that catalysts with Fe doping possessed larger specific surface area, stronger surface acidity, and can effectively reduce the

generation of ammonium salts and sulfates.

Key words: Low-temperature SCR;MnO_x/TiO₂ catalysts;Fe doping; Sulfur resistance

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1 研究背景和意义 1

1.2 MnO_x/TiO₂催化剂的应用研究 2

1.2.1 MnO_x/TiO₂催化剂的研究进展 2

1.2.2 SCR反应的反应机理 3

1.2.3 低温NH₃-SCR催化剂抗SO₂中毒机理 4

1.3 本课题主要研究内容 4

1.3.1 研究目标 5

1.3.2 研究内容 5

第二章 实验内容与方法 6

2.1 主要实验药品及试剂 6

2.2 主要实验仪器 6

2.3 催化剂的制备 6

2.3.1 MnO_x/TiO₂催化剂的制备 6

2.3.2 Fe-MnO_x/TiO₂催化剂的制备 7

2.4 催化剂活性及抗硫性测试 7

2.4.1 SCR脱硝实验装置 7

2.4.2 NO脱除率测试 8

2.5 催化剂的分析表征方法 9

2.5.1 比表面积和孔结构分析（BET） 9

2.5.2 X射线衍射分析（XRD） 9

2.5.3 氢气-程序升温还原分析（H₂-TPR） 9

2.5.4 催化剂的热稳定性测试（TGA） 9

3 Fe元素掺杂对MnO_x/TiO₂催化剂综合性能的影响研究 11

3.1 Fe元素掺杂MnO_x/TiO₂催化剂的性能与表征 11

3.1.1 Fe元素掺杂对催化剂脱硝性能的影响 11

3.1.2 催化剂X射线衍射分析 12

3.1.3 催化剂氢气-程序升温还原分析 13

3.1.4 催化剂热稳定性测试 14

3.1.5 催化剂比表面积测试 14

3.2 Fe掺杂对粉末状MnO_x/TiO₂催化剂抗硫性能的影响研究 15

3.2.1 SO₂对催化剂活性影响 15