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毕业论文网 > 毕业论文 > 材料类 > 新能源材料与器件 > 正文

还原热处理对铁镍纳米合金结构及及选择性催化加氢性能的影响研究毕业论文

 2021-11-17 11:11  

论文总字数:25123字

摘 要

随着社会的进步发展,现代化学工业愈发重要。在石油化工工业领域,人们对低碳烯烃的需求量就在不停增长,仅近几年,由于外卖行业的飞速发展,泡沫盒、塑料盒等有机化工产业产物的需求和发展一日千里。用廉价高效的方法制取低碳烯烃一直是世界学者研究石油化工的目标之一。乙烯等低碳烯烃作为重要的基础工业产物和原料,它的研究发展和整个行业息息相关。

现如今人们开发的制备低碳烯烃的技术工艺正在朝着多元化方向发展,其中现有的方法主要分为石油路线的石油裂解法和非石油路线的甲醇制烯烃法(MTO)、煤基合成气法(F-T)。在这几种方法中综合考虑,成本低、工艺短、产率高的石油裂解法还是工业领域主流的工艺手段。而阻碍石油裂解法制备低碳烯烃进一步发展的,除了石油资源本身产量和价格的限制外,还有在工艺上通过该方法制备出的产物经常混有炔烃或者二烯烃杂质。这些杂质的存在会使得低碳烯烃产物的纯度不符合下一步以低碳烯烃为原料的聚合反应生产活动,容易造成聚合反应催化剂失活。为了解决这个问题,工业生产中常通过选择性催化加氢的技术来除杂。完成这个催化加氢反应的重要要求就是有适合的催化剂,目前最实用的无疑是Pd基催化剂,在催化活性、选择性和稳定性方面都备受工业领域广泛认可。但是Pd本身的价格成本和储量的日益稀缺还是限制了Pd基催化剂在石油化工催化领域的发展。所以开发新的非贵金属催化剂来替代Pd基贵金属催化剂既是工业成本的需求,也是保护有限的Pd类资源,以及进一步发展低碳烯烃工业的需要。

经过理论和实验发现,单一Fe、Cu、Co、Ni等非贵金属想要替代Pd贵金属成为不饱和烃选择性催化加氢的催化剂还是存在催化性能上的差距。所以只能从不饱和烃的选择性加氢催化剂通常为负载型催化剂的特点入手,可以从催化剂成分除主要活性成分外的助催化剂和载体上出发进行催化剂改性,深入研究三者关系,构建纳米TiO2负载的FeNi3双金属催化剂体系,并从制备手段、还原退火温度、有序度、催化性能等方面进行了系统的实验分析。主要研究工作如下:

采用尿素共沉淀法将Fe源和Ni源同步沉积在TiO2载体上,对结构表征和性能进行测试,再研究Fe作助剂、纳米TiO2作载体的Ni基催化剂,通过高温下的氢气氩气混合气氛还原,选择不同退火温度以达到改变FeNi3/TiO2纳米合金催化剂结构和有序度的结果,从TG/DSC、磁性等测试手段中对有序度的改变进行验证。本文发现通过选择合适的退火温度,可以获得选择性和稳定性被提高了的FeNi3/TiO2催化剂。

关键词:非贵金属催化剂;FeNi3/TiO2纳米合金催化剂;有序度;退火温度

Abstract

With the development of society, the modern chemical industry is becoming more and more important. In the field of petrochemical industry, people's demand for low-carbon olefins is constantly increasing. In recent years, due to the rapid development of takeaway industry, the demand and development of organic chemical products such as foam boxes and plastic boxes are growing rapidly. The preparation of low-carbon olefins by low-cost and efficient methods has been one of the goals of world scholars in petrochemical industry. Low-carbon olefins such as ethylene are important basic industrial products and raw materials. Its research and development are closely related to the whole industry.

At present, the technological process for preparing low-carbon olefin developed by people is developing towards diversification direction, among which the existing methods are mainly divided into petroleum cracking method of petroleum route, methanol to olefin method (MTO) of non-petroleum route and coal-based synthesis gas method (F-T). Considering all these methods, the petroleum cracking method with low cost, short process and high yield is still the mainstream technology in the industrial field. However, the further development of the preparation of low-carbon olefins by petroleum cracking method is hindered not only by the limitation of the output and price of petroleum resources themselves, but also by the fact that the products prepared by this method are often mixed with alkynes or diene impurities. The existence of these impurities will make the purity of the low-carbon olefin product not conform to the next polymerization production activity using low-carbon olefin as raw material, which will easily cause deactivation of the polymerization catalyst. In order to solve this problem, selective catalytic hydrogenation is often used in industrial production to remove impurities. The important requirement for completing this catalytic hydrogenation reaction is to have suitable catalysts. At present, the most practical catalyst is undoubtedly Pd-based catalyst, which is widely recognized in the industrial field in terms of catalytic activity, selectivity and stability. However, the increasing scarcity of Pd's price, cost and reserves still limits the development of Pd-based catalysts in petrochemical catalysis. Therefore, the development of new non-noble metal catalysts to replace Pd-based noble metal catalysts is not only the demand of industrial costs, but also the need to protect the limited Pd resources and further develop the low-carbon olefin industry.

Through theory and experiments, it is found that there is still a gap in catalytic performance between single non-noble metals such as Fe, Cu, Co, Ni and other noble metals to replace Pd noble metals as catalysts for selective catalytic hydrogenation of unsaturated hydrocarbons. Therefore, we can only start with the characteristic that unsaturated hydrocarbon selective hydrogenation catalysts are usually supported catalysts. We can start from the cocatalyst and carrier of the catalyst components except the main active components to carry out catalyst modification. We can deeply study the relationship among the three, construct FeNi3 bimetallic catalyst system supported by nano-TiO2, and carry out systematic experimental analysis from the aspects of preparation methods, reduction annealing temperature, order degree, catalytic performance, etc. The main research work is as follows:

The Fe source and Ni source were simultaneously deposited on TiO2 carrier by urea coprecipitation method, and the structure characterization and performance were tested, The Ni-based catalyst with Fe as auxiliary agent and nano-TiO2 as carrier is further studied, and is reduced by hydrogen and argon mixed atmosphere at high temperature. Different annealing temperatures were selected to change the structure and order of FeNi3/TiO2 nano alloy gold catalyst. The change of order degree was verified by TG/DSC, magnetism and other testing methods. It is found in this paper that FeNi3/TiO2 catalyst with improved selectivity and stability can be obtained by selecting suitable annealing temperature.

Key Words:Non-noble metal catalyst;FeNi3/TiO2 nano alloy catalyst;Degree of order; Annealing temperature

目录

摘 要 I

Abstract II

第1章 绪论 1

1.1 引言 1

1.2 还原热处理方法的概述 2

1.3 双金属纳米载体合金催化剂的概述 2

1.3.1 双金属的作用—第二组分金属的添加 2

1.3.2 金属的组合方式—合金相固溶体 3

1.3.3 合金的有序度 3

1.3.4 纳米载体 4

1.4 不饱和烃选择性催化加氢反应的概述 5

1.4.1 不饱和烃选择性催化加氢反应背景 5

1.4.2不饱和烃选择性催化加氢反应历程 5

1.4.3不饱和烃选择性催化加氢反应催化剂 6

1.5 课题的提出背景 7

1.6 论文思路及内容 8

第2章 TiO2负载FeNi3纳米合金催化剂的制备及其性能研究 9

2.1 引言 9

2.2 实验部分 10

2.2.1 实验试剂及仪器 10

2.2.2 实验过程 10

2.2.3 结构表征和性能测试 11

2.3 实验结果与讨论 13

2.3.1 FeNi3/TiO2纳米合金催化剂的结构特征 13

2.3.2 FeNi3/TiO2催化剂的1, 3-丁二烯选择性催化加氢性能测试 15

2.4 本章小结 17

第3章 结论与展望 16

3.1 结论 16

3.2 展望 17

参考文献 18

致 谢 20

附 录 21

第1章 绪论

    1. 引言

石油化工工业,即以石脑油和天然气为原料,以加工生产石油产品和石油化工产品为目的的现代化重要工业,是国民经济的重要支柱,是我国主要的能源消费主体。目前,化石能源作为当今时代的最主要的能源,在世界能源消费结构中占主导地位,在我国能源消费结构中占比高达85%以上[1],甚至到2050年,化石能源还是大概率会占据能源供给中的主导地位[2]

在石油化工工业中,烯烃是重要产物之一,其中,以乙烯为代表的碳原子数小于或等于4的烯烃扮演着不可或缺的角色,如乙烯就是衡量一个国家化工工业发展程度的重要指标。生活中大家所接触的现代有机工业产品,绝大多数都离不开低碳烯烃,如表1.1所示:

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