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毕业论文网 > 毕业论文 > 化学化工与生命科学类 > 化学工程与工艺 > 正文

Au-Mn合金纳米粒子催化选择氧化甲苯性能研究毕业论文

 2022-01-13 21:43:51  

论文总字数:23401字

摘 要

芳烃的选择性氧化在学术界和工业界都非常重要。从经济和环境的角度来看,危险石油副产品,如甲苯和挥发性有机化合物,氧化成其他有用的化学品越来越受到的关注。甲苯的非选择性氧化会产生很多产物,诸如苯甲醇、苯甲醛、苯甲酸、苯甲酸酯和苯酚等。通过烃类的选择性氧化可以生产醛类、醇类、酸类以及酯类等重要的化工产品,它们在化工行业中具有重要的商业应用和经济价值。而甲苯作为化工行业常见的石油产物,其氧化产物苯甲醛、苯甲醇、苯甲酸以及苯甲酸苄酯在化工行业中具有重要的地位和广泛的用途。

在甲苯液相氧化反应中,影响甲苯的转化率和目标产物的选择性的因素较多,主要有温度、压力、时间以及催化剂的使用量和催化剂的种类,其中目前研究最多的是催化剂的种类对反应的影响。工业上现在多采用以过渡金属为主的均相催化剂进行甲苯液相氧化反应。无溶剂甲苯液相氧化法具有操作简单、反应条件温和、选择性高等优点。已经进行了许多努力来提高在挥发性有机溶剂中使用多相催化体系在液相中氧化甲苯的效率。本课题以溶胶沉淀法制备Au-Mn/TiO2多相催化剂,进行无溶剂的甲苯液相分子氧氧化反应。该反应在高压釜中进行,以纯甲苯为原料,Au-Mn/TiO2为催化剂,氧气为氧化剂,研究该催化剂对甲苯液相氧化催化反应的影响。

(1)在此次课题中,采用溶胶沉淀法制备Au-Mn/TiO2催化剂,该催化剂在催化氧化甲苯的时候,具有良好的催化活性和稳定性。本次课题设定的反应条件是:甲苯10mL,氧气压力1MPa,催化剂负载量为2%,用量0.6g,温度200°C,反应时间10h。当金属摩尔比Au:Mn达到3:1时,甲苯的转化率为10.6%,苯甲醛的选择性为36.5%。

(2)为了使甲苯的转化率得到提高的同时,使得反应对苯甲醛和苯甲醇有更高的选择性。在该项目中,通过改变负载金属的摩尔比,温度,催化剂加入的量等影响因素,设计出最佳的反应条件和催化剂。并且采用X射线衍射(XRD)、扫描电镜(SEM)和N2—吸附脱附等表征措施对催化剂的结构和性能进行了表征。

综上所述,本课题秉持绿色环保的理念,产物中不仅没有氯,提高了产物的应用行业范围,另外,克服了催化剂难以回收等缺点。除此以外,本课题中的催化剂使得氧化反应中甲苯的转化率相比前人的文献较高,同时苯甲醛的选择性很高。上述实验结果不仅仅表明了催化剂只局限于过渡金属,更重要的一点是:拓宽了甲苯氧化反应的研究领域,并且进一步拓展了贵金属Au的催化剂用于甲苯氧化的研究。

关键词:甲苯 苯甲醛 苯甲醇 苯甲酸 催化氧化

Selective Study on Catalytic Oxidation of Toluene by Au-Mn/TiO2

ABSTRACT

Selective oxidation of aromatic hydrocarbons makes all the difference in community of scholar and has high industrial application value. From an economic and environmental point of view, the oxidation of hazardous petroleum byproducts, such as toluene and volatile organic compounds, to other useful chemicals has attracted increasing attention. Non-selective oxidation of toluene generates a series of products, including benzyl alcohol, benzaldehyde, benzoic acid, benzoate, and phenol. Aldehydes, alcohols, acids, esters and other important chemical products can be produced by selective oxidation of hydrocarbons. They have important commercial applications and economic values in the chemical industry. Toluene is a common petroleum product in the chemical industry. The oxidation products of toluene have an important position and are widely used in the chemical engineering.

There are many factors that affect the liquid phase oxidation of toluene, mainly including temperature, pressure, time, catalyst usage and catalyst types, among which the most studied one is the effect of catalyst types on the reaction. At present, homogeneous catalysts mainly composed of manganese ions and cobalt ions are widely used in industry to carry out liquid phase oxidation of toluene. In this paper, Au-Mn/TiO2 catalyst is prepared by sol precipitation method to carry out solvent-free liquid phase molecular oxygen oxidation of toluene. In addition, the reaction will be carried out in an autoclave with pure toluene as raw material, Au-Mn/TiO2 as catalyst and oxygen as oxidant. The catalysts were made by sol-gel method and their effect on this reaction will be researched. The main conclusions of this paper are as follows:

(1) In the reaction, some of the catalysts showed good performance. The process conditions were as follows: toluene 10mL, PO2 1MPa, 2% load of Au-Mn/TiO2, catalyst amount 0.6g, temperature 200°C, reaction time 10h. When the molar ratio of Au: Mn reached 3: 1, the conversion rate of toluene was 10.6%, and the selectivity of benzaldehyde was 36.5%.

(2) In order to improve the conversion of toluene and the selectivity of benzaldehyde and benzyl alcohol, the optimum reaction conditions and catalysts were selected by changing the molar ratio of supported metals, temperature and the amount of catalyst added in the reaction. The catalytic performances and properties were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and N2-Sorption.

As stated above, this subject adheres to the belief of green and environmental protection. The product is not only free of chlorine, which improves the application scope of the product, but also overcomes the shortcomings of difficult recovery of catalyst. In addition, the catalyst in this topic makes the toluene oxidation reaction have a better conversion rate, at the same time, it also makes the selectivity of benzaldehyde improved. The above experimental results broaden the research field of catalysts for toluene oxidation reaction, and further expand the catalytic research of transition metal Mn and noble metal Au.

Key words: Toluene Benzaldehyde Benzyl alcohol Benzoic acid Catalytic Oxidation

目录

摘 要 I

ABSTRACT III

第一章 文献综述 1

1.1 引言 1

1.2 甲苯、苯甲醛、苯甲醇以及苯甲酸的性质、应用和生产消费现状 2

1.2.1 甲苯的性质和应用 2

1.2.2 苯甲醛的性质和应用 3

1.2.3 苯甲醇的性质和应用 4

1.2.4 苯甲酸的性质和应用 4

1.3全球苯甲醛的消费现状和生产工艺现状 5

1.4 苯甲醇的生产状况分析 5

1.5 甲苯液相氧化反应机理 5

1.6 甲苯液相氧化研究进展 6

1.6.1 甲苯液相氧化催化剂研究进展 6

1.6.2 工艺研究进展 7

1.7 论文研究内容 9

第二章 实验方法 11

2.1 原料试剂与实验设备 11

2.2 甲苯氧化产物分析方法 12

2.3 催化剂表征 13

2.4 催化剂活性评价 13

第三章 Au-Mn/TiO2催化剂上甲苯分子氧催化氧化研究 15

3.1 催化剂制备 15

3.2 催化剂表征 15

3.2.1 XRD 15

3.2.2 SEM 16

3.2.3 BET 17

3.3 Au与Mn摩尔比的影响 17

3.4 温度的影响 18

3.5 催化剂用量的影响 19

3.6 Au-Mn/TiO2催化剂稳定性考察 20

第四章 结论与展望 22

4.1 结论 22

4.2 展望 22

参考文献 24

致谢 27

第一章 文献综述

1.1 引言

芳烃进行分子氧的液相氧化具有重要的商业意义[1]。在现代化学工业中,从经济和环境的角度来看,分子氧液相氧化芳烃是一个非常有吸引力的过程,通过这种方法可以生产一系列有价值的含氧化合物[2]。甲苯在石油化工行业中来源广泛,价格低廉,生产量大。目前,甲苯的氯化水解法是目前苯甲醛的主要生产方法,但是,该方法污染严重,工业流程复杂,且产品中含有氯,限制了苯甲醛在医药等特殊行业的应用。同样具有较高的商业价值的苯甲醇在香料、涂料、染料等方面也有着重要的应用价值。目前,除了氯化水解法,甲苯液相氧化也实现了工业化生产,但是由于苯甲醛和苯甲醇作为中间产物,目前在这个方法中的收率较低。因此,在甲苯液相氧化反应中,提高反应的选择性引起了学术界和工业界的广泛研究。然而,反应本身是非选择性的,许多的措施增加了不希望的副产品的出现,这增加了工艺成本,因为随后需要很多纯化步骤。

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