论文总字数：29751字

摘 要

氮氧化物（NO_x）是雾霾及恶化大气质量的主要成因之一，国家已将NO_x的减排列为大气污染治理的重点。现有脱硝技术中，选择性催化还原（SCR）技术脱硝效率高、稳定性好，成为当前国内外烟气脱硝的主流技术和发展方向^[1]，其技术核心是脱硝催化剂。目前，国内外使用较为普遍的商用烟气脱硝催化剂为矾基催化剂，但其活性组分V₂O₅有毒，不仅在生产和使用中存在污染，废弃后还会危害环境安全，国家生态环境部已于2014年将废钒基脱硝催化剂列为危废监管，我国自主研发的稀土基脱硝催化剂环境友好，活性温度窗口范围宽，机械强度高，运行稳定性好，于2016年被国家三部委指定为矾基脱硝催化剂的替代品。

本文综述了国内外脱硝催化剂的研究进展，提出了稀土铈基脱硝催化剂是一种最有应用前景的烟气脱硝催化材料。以课题组前期制备的CeO₂/Al₂O₃催化剂为研究对象，深入研究其活性影响因素和SO₂中毒机理。研究发现，以γ-Al₂O₃为载体，以单一CeO₂为催化活性组分的CeO₂/Al₂O₃催化剂高温水热稳定性差，脱硝效果受水蒸气和SO₂影响大。为进一步增强CeO₂/Al₂O₃催化剂的高温水热稳定性能及抗水硫中毒能力，本论文通过Zr⁴ 、Mo⁶ 、Fe³ 、Cu² 等过渡金属离子掺杂，以此构建新型的铈基复合氧化物催化剂体系，明显改善了催化剂的水热稳定性能；催化剂的表面酸性显著增强，弱化了SO₂的吸附，从而增强了抗水硫中毒能力。实验结果表明，以γ-Al₂O₃载体质量为基础，负载0.1wt.%过渡金属Mo时催化剂的NO转化率达到98.48%，并且抗H₂O和SO₂中毒能力明显提升。

关键词：烟气脱硝 CeO₂/Al₂O₃脱硝剂 过渡金属离子掺杂 抗水硫中毒性能

ABSTRACT

Nitrogen oxides (NO_x) are one of the main causes of smog and deteriorating air quality. The country has ranked NO_x reduction as the focus of air pollution control. Among the existing denitration technologies, selective catalytic reduction (SCR) technology has high denitration efficiency and good stability, and it has become the mainstream technology and development direction of flue gas denitration at home and abroad ^[1], and its technical core is a denitration catalyst. At present, the most commonly used commercial flue gas denitration catalysts are alum-based catalysts, but the active component V₂O₅ is toxic. Not only is there pollution in production and use, but it will also endanger the safety of the environment after being discarded. In 2014, the waste vanadium-based denitration catalyst was listed as hazardous waste supervision. Chinese self-developed rare earth-based denitration catalyst is environmentally friendly, which has a wide active temperature window, high mechanical strength, and good operating stability. It was designated as alum-based by three national ministries and commissions in 2016 alternatives to denitration catalysts.

This paper reviews the research progress of denitration catalysts at home and abroad, and proposes that rare earth cerium-based denitration catalysts are the most promising catalytic materials for flue gas denitration. Taking the CeO₂/Al₂O₃ catalyst prepared in the early stage of the research group as the research object, the influential factors of its activity and the mechanism of SO₂ poisoning were thoroughly studied. The study found that CeO₂/Al₂O₃ catalyst with γ-Al₂O₃ as the carrier and single CeO₂ as the catalytically active component has poor hydrothermal stability at high temperature, and the denitration effect is greatly affected by water vapor and SO₂. In order to enhance the high-temperature hydrothermal stability of CeO₂/Al₂O₃ catalyst and its ability to resist water and sulfur poisoning, this paper uses Zr⁴ , Mo⁶ , Fe³ , Cu² and other transition metal ion doping to construct a new cerium-based composite oxide catalyst system. The hydrothermal stability of the catalyst is significantly improved; the surface acidity of the catalyst is significantly enhanced, which weakens the adsorption of SO₂, thereby enhancing the resistance to water and sulfur poisoning. The experimental results show that, based on the mass of the γ-Al₂O₃ carrier, the NO conversion rate of the catalyst reaches 98.48% when the 0.1wt.% transition metal Mo is loaded, and the resistance to H₂O and SO₂ poisoning is significantly improved.

Key Words: Flue gas denitration;CeO₂/Al₂O₃ denitration agent;Transition metal ion doping; Resistance to water and sulfur poisoning

目 录

摘 要 I

ABSTRACT II

第一章 绪论 1

1.1 课题背景 1

1.2 选择性催化还原法 1

1.3 SCR催化体系研究现状 3

1.3.1 锰基催化剂 3

1.3.2 矾基催化剂 4

1.3.3 铈基催化剂 5

1.4 SCR催化剂性能的影响因素 6

1.4.1 催化剂载体的影响 6

1.4.2 助剂对催化剂性能影响 6

1.4.3 H₂O、SO₂对催化剂活性影响 6

1.4.4 碱中毒对催化剂活性影响 7

1.5 SCR催化剂改性 8

1.5.1 制备方法改进 8

1.5.2 过渡金属掺杂 8

1.6 本文研究内容 9

第二章 实验方法 10

2.1 化学试剂和药品 10

2.2 实验仪器 11

2.3 催化剂活性评价与测试 11

2.3.1 催化剂活性评价 11

2.3.2 XRD测试 12

2.3.3 SEM测试 12

2.3.4 BET测试 12

2.3.5 H₂-TPR测试 12

第三章 CeO₂/Al₂O₃体系催化剂制备与性能研究 13

3.1 CeO₂/Al₂O₃催化剂制备 13

3.1.1 催化剂制备流程 13

3.2 过渡金属掺杂催化剂的制备与性能研究 14

3.2.1 催化剂制备 14

3.2.2 催化剂活性测试 14

3.3 催化剂表征 16

3.3.1 催化剂XRD分析 16

3.3.2 催化剂SEM分析 16

3.3.3 催化剂氧化还原性能分析 17

第四章 Mo掺杂催化剂抗中毒性研究 18

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