碳纳米管负载铁酞菁的制备及其催化性能的研究

发布时间：2018-05-26 01:44

  本文选题：轴向配体 + 催化氧化　； 参考：《浙江理工大学》2016年硕士论文

【摘要】：环境水污染中酚类化合物是一种来源广泛,难以降解,对自然环境有着巨大危害的有机污染废水,是国内外要求被严重控制的有机污染物之一。对传统的高级氧化技术,催化体系常常含有H2O2利用率低、对难降解的有机污染物催化活性差、催化剂难以重复使用等问题。因此开发一种高效绿色的去除废水中有毒目标污染物的催化体系具有重要意义。金属酞菁类化合物与细胞色素P-450的活性中心金属卟啉结构相似,具有类似于生物酶的催化活性和选择性,其催化过程是通过中心金属离子与反应物发生配位进行的。碳纳米管具有独特的物理性质和结构、优良的电化学性能、大的比表面积、较好的物理吸附能力以及在很多条件下均具有较高的稳定性,决定了其可以作为非均相催化剂的理想载体材料。因此,可以将具有模拟酶催化剂的金属酞菁负载到改性的碳纳米管上,研究催化体系的催化性能,探索负载型催化剂的改善方法。本文利用两种不同的配体(4-氨基吡啶(Py)和巯基乙胺(CS))改性碳纳米管,分别使用脱氨基法和酰胺化方法改性碳纳米管得到MWCNTs-Py和MWCNTs-CS,再通过轴向配位的思想制备合成两种碳纳米管轴向负载金属酞菁催化剂(FePc-Py-MWCNTs, FePc-CS-MWCNTs)。采用UV-vis、XPS、FTIR等方法对催化剂进行表征结果表明FePc成功地通过轴向配位的方式负载到碳纳米管上。选用对氯苯酚(4-CP)作为目标污染物,H2O2为氧化剂,研究催化剂的催化氧化能力。实验结果表明：FePc-Py-MWCNTs/H2O2体系在酸性条件下相对于FePc/MWCNTs/H2O2体系具有较高的活性,说明配体的引入可以极大地改善催化体系的活性；FePc-CS-MWCNTs/H2O2体系相较与FePc-Py-MWCNTs/H2O2体系,无论是酸性条件还是中性条件都具有很好的催化活性,且催化剂的循环使用性要高得多。EPR测试两个催化体系都有羟基自由基(·OH)和过氧自由基(·OOH)的存在,表明二者反应都是一个羟基自由基为主导的反应,这与传统的含有配体存在的催化体系由高价金属主导的反应不同。在本论文的催化体系中,由于轴向配体对中心金属Fe的供电子效应使得FeⅢ/Ⅱ的氧化电位更低,加快了在传统Fenton反应体系中FeⅢ向FeⅡ的转化过程。本论文的研究提供了一种通过轴向配位的方法制备合成负载型催化剂,为催化剂的改善和催化体系的优化设计奠定了一定的基础。
[Abstract]:Phenolic compounds in environmental water pollution are one of the organic pollutants which are widely available and difficult to degrade and have great harm to the natural environment. They are one of the organic pollutants which are required to be seriously controlled at home and abroad. For the traditional advanced oxidation technology, the catalytic system often contains low utilization rate of H2O2, poor catalytic activity for refractory organic pollutants, and difficult to reuse the catalyst. Therefore, it is of great significance to develop an efficient green catalytic system for removing toxic target pollutants from wastewater. Metal phthalocyanines are similar to cytochrome P-450 in the structure of active center metalloporphyrins and have catalytic activity and selectivity similar to those of biological enzymes. The catalytic process of metal phthalocyanines is carried out by the coordination of central metal ions with reactants. Carbon nanotubes have unique physical properties and structure, excellent electrochemical performance, large specific surface area, good physical adsorption ability and high stability under many conditions. It is determined that it can be used as an ideal support material for heterogeneous catalysts. Therefore, the metal phthalocyanine with mimic enzyme catalyst can be loaded on the modified carbon nanotubes to study the catalytic performance of the catalyst system and explore the improvement methods of the supported catalyst. In this paper, two different ligands (4-aminopyridine) and mercaptoethylamine (CSA) were used to modify carbon nanotubes. MWCNTs-Py and MWCNTs-CSwere prepared by deamination method and amidation method respectively. Then two kinds of carbon nanotubes supported metal phthalocyanine catalysts FePc-Py-MWCNTsand FePc-CS-MWCNTswere synthesized by the idea of axial coordination. The characterization of the catalyst by UV-vis-XPS-FTIR showed that FePc was successfully loaded onto carbon nanotubes by axial coordination. The catalytic oxidation ability of the catalyst was studied by using p-chlorophenol 4-CP) as the target pollutant H _ 2O _ 2 as oxidant. The experimental results show that the FePc-Py-MWCNTsH _ 2O _ 2 / H _ 2O _ 2 system has higher activity than that of FePc/MWCNTs/H2O2 system in acidic condition, which indicates that the introduction of ligand can greatly improve the activity of FePc-CS-MWCNTs / H _ 2O _ 2 system compared with FePc-Py-MWCNTs/H2O2 system. Both acidic and neutral conditions had good catalytic activity, and the reusability of the catalysts was much higher. EPR showed that there were hydroxyl radical (OH) and peroxy radical (OOH) in both systems. It is shown that both reactions are dominated by hydroxyl radical, which is different from the traditional catalytic system containing ligand, which is dominated by high valence metal. In the catalytic system of this thesis, the oxidation potential of Fe 鈪，

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