论文总字数：18816字

摘 要

柴油机排放的碳烟颗粒物具有致癌性，并且许多国家颁布了严格的排放法规。通过简易的水热法合成整体式水钠锰矿型MnO₂/Ni催化剂，并进行XRD、Raman光谱、N₂吸附-脱附、SEM、H₂-TPR等表征。结果表明，涂层重量与水热温度成正比，其中在160 ℃下合成的样品显示最低T₅₀ (418 ℃) 和低涂层剥离脱落率 (0.45±0.11 wt.%) 。多孔Ni基底紧紧覆盖有交联的花状水钠锰矿二氧化锰涂层将提供许多有效的捕获碳烟颗粒的位置。纳米花和Ni衬底之间的中间相NiMnO₃会稳定纳米花状MnO₂，并抑制向无序纳米棒的转变。水钠锰矿中的钾元素可活化O₂形成表面活性氧，提高氧化还原性质。而且，Ni² /Ni³ 可以增强K-O键，抑制K 热蒸发，提高抗水性能，赋予催化剂良好的重复使用性。催化剂中的钾含量比接触点更能提高催化活性。该备选催化剂可能是一种有前途的整体式催化剂，用于净化真实的柴油机废气，并且该方法可用于合成用于其它催化应用的新型单体金属催化剂。

关键词：整体式催化剂 水钠锰矿MnO₂ 相间强化 碳烟氧化 脱落率

Interphase Strengthening Birnessite MnO₂ Coating on Three-Dimensional Ni Foam for Soot Removal

Abstract

The soot particulates emitted from diesel engines have been ultimately evidenced cancerogenic and successive rigorous emission legislations have been approved in many countries. Monolithic metal-based purification materials are able to tackle the harsh working conditions. Hence, monolithic birnessite MnO₂/Ni foam catalysts were facilely synthesized via a hydrothermal route and characterized by XRD, Raman spectra, N₂ adsorption-desorption, SEM, H₂-TPR, et al. The coating weights are in proportion to hydrothermal temperatures. And the sample synthesized at 160 ℃ displays the lowest T₅₀ (418 ℃) and the coating exfoliation is only 0.45±0.11 wt.%. Porous Ni substrate tightly covered with a layer of crosslinked flowerlike birnessite MnO₂ coating would provide many available sites capturing soot particulates. The interphase NiMnO₃ between nanoflowers and Ni substrate could intensify nanoflowers against exfoliation, and inhibit transformation into disordered nanorods. Potassium in the birnessite may activate gas O₂ effectively forming surface oxygen and improve the redox properties. Moreover, Ni² /Ni³ dopants inhibit K thermal evaporation and water dissolution via strengthening K-O band, therefore endow good reusabilities. It is the K contents in the composites rather than contact points that determine activities. This candidate is likely a promising monolithic catalyst purifying the real diesel engines exhaust. And the method could be employed to synthesize novel monolithic metallic catalysts for other catalytic applications.

Key words: Monolithic catalyst; Birnessite MnO₂; Interphase strengthening; Soot oxidation; Exfoliation

目 录

摘要 I

ABSTRACT II

第一章 绪论 1

1.1 引言 1

1.2 碳烟颗粒物 (PM) 2

1.2.1 碳烟颗粒物的介绍 2

1.2.2 碳烟颗粒物的去除方法 2

1.3 碳烟的催化燃烧过程 3

1.3.1 碳烟颗粒物的催化燃烧机理 3

1.3.2 催化剂 3

1.4 研究意义与内容 4

第二章 实验部分 6

2.1 化学试剂及实验仪器 6

2.1.1 化学试剂 6

2.1.2 实验仪器 6

2.2 整体式催化剂的制备 6

2.3 催化剂表征 7

2.4 催化性能 7

2.4.1 碳烟氧化 8

2.4.2 重复使用性 8

2.5 牢固性测试 8

第三章 实验结果与分析 9

3.1 结构分析 9

3.2 形貌研究 11

3.3 H₂-TPR 13

3.4 催化性能 14

3.4.1 碳烟氧化 14

3.5 牢固性测试 15

第四章 结论与展望 17

4.1 结论 17

4.2 展望 17

参考文献 18

致谢 21

第一章 绪论

1.1 引言

机动车的数量随着经济社会的快速发展而增多，尽管能够让我们的日常生活更加方便快捷，但是汽车尾气量大幅上升，尾气成分中的一氧化碳、碳氢化合物、固体悬浮颗粒物和氮氧化合物均是雾霾主要污染物^[1]。

当前社会很多国家都有雾霾环境问题，严重影响着人们的生活水平与健康状况，引起了大众对空气环境中颗粒物的关注。

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