氧化石墨烯π-π非共价键负载四（对—羧基苯基）金属卟啉催化性能研究

发布时间：2018-07-17 07:39

【摘要】：细胞色素P-450酶是一种自然界广泛存在的生物催化剂,其是由原卟啉铁和蛋白质形成的空腔结构生物酶。该生物酶给绿色工业仿生催化剂提供了一个很好的模型。人们在用载体固载金属卟啉模拟细胞色素P-450酶的结构功能时,试图通过各种配位作用来调节金属卟啉的催化活性,研究其影响催化活性的本质;也试图通过改变载体的比表面积来提高固载的金属卟啉中心暴露于氧化剂和被催化氧化底物的接触率。研究结果显示,载体和金属卟啉之间的配位作用会改变金属离子和轴向配体的电子云密度,从而,促进了金属卟啉的催化活性。此外,载体比表面积越大,金属离子就会分散的越均匀,其催化活性也就越高。因此,本工作采用具有路易斯碱特色结构(大π电子结构特色)和大比表面积及其较好稳定性且环保的氧化石墨烯作为载体,模拟细胞P-450的蛋白质载体和高比表面的空腔结构,特别是利用氧化石墨烯特殊的π电子结构,通过π-π非共价键作用把金属卟啉负载上去,以调节金属卟啉中心离子的正电性并有效分散催化中心金属离子,来探索提高所固载的金属卟啉的催化活性。以甲苯作为探针,去探究这些氧化石墨烯固载金属卟啉催化氧化甲苯的性能。本工作的研究内容如下:1.简单介绍金属卟啉、氧化石墨烯以及甲苯的催化氧化研究进展。2.通过参考相关的文献,合成氧化石墨烯(GO)、四(对-羧基苯基)金属卟啉(M TCPP Cl),以及运用π-π非共价键作用合成负载催化材料M TCPP Cl/GO。3.使用傅里叶红外光谱法(FT-IR)、紫外光谱分析法(UV-vis)、X射线光电子能谱分析(XPS)、扫描电子显微镜(SEM)、热重分析(TG)以及比表面积测试(BET)等方法,对GO、M TCPP Cl和M TCPP Cl/GO进行表征分析,确定其结构、固载方式以及稳定性。4.通过单因素变量法探究其催化氧化甲苯的性能。探究反应温度、压力、时间以及催化剂使用量等因素对催化材料的催化性能的影响,获得最佳反应条件,并在此基础下,重复利用三种负载催化剂催化氧化甲苯,研究负载金属卟啉的催化性能和其结构之间的关系。5.实验结果表明,四(对-羧基苯基)锰卟啉(Mn TCPP Cl)、四(对-羧基苯基)铁卟啉(Fe TCPP Cl)以及四(对-羧基苯基)钴卟啉(Co TCPP Cl)催化氧化甲苯的产率、转化率以及转化数都没有其相应的负载催化材料好。而且,三种金属卟啉只能催化使用一次,而三种负载催化材料均可重复使用4次,且重复催化效果稳定。其中,CoTCPP Cl/GO重复催化甲苯的平均转化率和产率要比Co TCPP Cl的催化结果高2.80%和0.73%。而在最佳条件下,其首次催化甲苯的转化率和产率要比Co TCPP Cl提高了1.79%和1.30%。此外,综合考虑催化温度、压力、时间等因素,三种负载催化材料的催化活性大小分别为Mn TCPP Cl/GOCo TCPP Cl/GOFe TCPP Cl/GO。6.通过对照实验结果并参考相关文献,初步推断三种负载催化材料催化氧化甲苯的反应机理可能为自由基反应机理。
[Abstract]:Cytochrome P-450 enzyme is a widely existed biocatalyst in nature. It is a hollow structure enzyme formed by protoporphyrin iron and protein. This enzyme provides a good model for green industrial bionic catalyst. When we imitated the structure and function of cytochrome P-450 enzyme by carrier immobilized metalloporphyrins, we tried to regulate the catalytic activity of metalloporphyrin by various coordination actions, and to study the nature of its influence on the catalytic activity. It is also attempted to increase the contact rate of the supported metalloporphyrin center exposed to oxidant and catalytic oxidized substrate by changing the specific surface area of the carrier. The results show that the coordination between support and metalloporphyrin can change the electron cloud density of metal ions and axial ligands and thus promote the catalytic activity of metalloporphyrins. In addition, the larger the specific surface area of the carrier, the more uniform the metal ions will be, and the higher their catalytic activity. Therefore, in this work, graphene oxide with large specific surface area and high specific surface area and good stability were used as carriers to simulate the protein carrier of P-450 cell and the cavity structure of high specific surface, which were characterized by Lewis base structure (large 蟺 electron structure) and high specific surface area. In particular, the special 蟺 electronic structure of graphene oxide is used to support metalloporphyrins by 蟺-蟺 noncovalent bonding, so as to regulate the positive electrical properties of metalloporphyrin central ions and effectively disperse the catalytic center metal ions. To improve the catalytic activity of the supported metalloporphyrin. Toluene was used as a probe to study the catalytic performance of these graphene supported metalloporphyrins in the oxidation of toluene. The contents of this work are as follows: 1. The progress of catalytic oxidation of metalloporphyrin, graphene oxide and toluene is introduced briefly. In this paper, graphene oxide (go), tetra (p-carboxyphenyl) metalloporphyrin (MTCPP Cl) and supported catalyst material M TCPP / Cl / GO.3 were synthesized by referring to related literatures. GOM TCPP Cl and M TCPP Cl-go were characterized by Fourier transform infrared spectroscopy (FT-IR), UV-vis X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TG) and specific surface area measurement (BET). Fixation mode and stability. 4. The catalytic oxidation of toluene was investigated by single factor variable method. The effects of reaction temperature, pressure, time and amount of catalyst on the catalytic performance of the catalyst were investigated, and the optimum reaction conditions were obtained. On this basis, three kinds of supported catalysts were reused to catalyze the oxidation of toluene. The relationship between the catalytic activity and the structure of the supported metalloporphyrin was studied. The results show that tetra (p-carboxyphenyl) manganese porphyrin (mn TCPP Cl), tetra (p carboxyl phenyl) iron porphyrin (Fe TCPP Cl) and tetra (p carboxyl phenyl) cobalt porphyrin (Co TCPP Cl) catalyze the oxidation of toluene. The conversion rate and the conversion number are not as good as their corresponding supported catalytic materials. Moreover, the three metalloporphyrins can only be used once, while the three kinds of supported catalytic materials can be reused for 4 times, and the catalytic effect of the three kinds of metalloporphyrins is stable. The average conversion and yield of toluene catalyzed by CoTCPP Cl / go were 2.80% and 0.73% higher than that of Co TCPP Cl. Under the optimum conditions, the conversion and yield of toluene were 1.79% and 1.30% higher than that of Co TCPP Cl for the first time. In addition, considering the factors of catalytic temperature, pressure and time, the catalytic activity of the three supported catalytic materials is mn TCPP Cl / GOCo TCPP Cl / GOFe TCPP Cl / GOP Cl / GOP Cl / GOG 路6, respectively. By comparing the experimental results and referring to the relevant literature, it is preliminarily inferred that the reaction mechanism of the three supported catalytic materials for the oxidation of toluene may be the mechanism of free radical reaction.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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