基于2,4,6-三（1-咪唑基）-1,3,5-三嗪的多酸杂化物的合成及其光降解性质研究

发布时间：2018-03-11 21:09

本文选题：Keggin多酸　切入点：光敏剂　出处：《东北师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：杂多酸是一种绿色催化剂,具有活性高、选择性好、无毒性、不腐蚀设备等优点。大量的研究工作表明在光激发作用下,激发态的多酸具有很强的氧化能力,可以有效地降解有机污染物。然而,该类催化剂易溶于水且在催化反应条件下稳定性差,这使其不易回收重复利用。其中,Keggin型钨系多酸尽管具有很好的光催化活性,但是其只能利用太阳光中的紫外光,这限制了其在实际中的应用。制备基于多酸有机无机杂化物是当前解决这一缺陷的有效途径之一。通过引入有机物光敏剂,与多酸形成一种杂化物,这样既能够形成非均相的催化剂,实现催化剂的循环再利用,又能增加其在可见光下的催化活性。因此,寻找合适的光敏剂备受人们的关注。本论文则选用黄色的有机物2,4,6-三(1-咪唑基)-1,3,5-三嗪(TIT)作为光敏剂,经酸化后,分别与Keggin型磷钨酸和硅钨酸通过简单的共沉淀法,制备了两个黄色的非水溶性的有机无机杂化物:TITH-PW12和TITH-SiW12。我们通过使用UV-vis,FT-IR,SEM等手段对其组成进行了表征,探究了在可见光照射下对甲基橙溶液(MO)催化降解活性,并初步探讨了它们的催化降解机理。实验结果表明,杂化物中多酸(PW12和SiW12)在沉淀过程中结构是保持完整的,同时,发现所得的杂化物在可见光区的吸收大大增加。在可见光的照射下,化合物TITH-PW12和TITH-Si W12不需加任何氧化剂就能够将甲基橙(MO)溶液完全降解,显示了很好的催化活性。催化剂易于从反应体系分离、回收,而且重复利用四次后,其结构及催化活性仍保持不变,催化降解满足一级动力学方程。同时发现,当选用同一种光敏剂而改变Keggin型杂多酸不同时,所形成的复合物的催化活性没有明显的变化。因此,光敏剂的选择对降解染料催化活性起着至关重要的作用。
[Abstract]:Heteropoly acid is a kind of green catalyst with high activity, good selectivity, non-toxicity, non-corrosive equipment and so on. A large number of studies show that excited polyacids have strong oxidation ability under photoexcitation. However, this kind of catalyst is easy to dissolve in water and has poor stability under the condition of catalytic reaction, which makes it difficult to recover and reuse. However, it can only use ultraviolet light in the sun, which limits its practical application. The preparation of polyacid-based organic-inorganic hybrids is one of the effective ways to solve this defect. A hybrid is formed with polyacid, which can form heterogeneous catalysts, recycle the catalysts, and increase their catalytic activity under visible light. In this paper, the yellow organic compounds (2x4, 6-, 3-triamidazolyl) were chosen as Guang Min. After acidification, they were treated with Keggin phosphotungstic acid and silicotungstic acid by simple coprecipitation method, respectively. Two yellow insoluble organic-inorganic hybrids: TITH-PW12 and TITH-SiW12were prepared. Their composition was characterized by UV-vis-FT-IR SEM, and the catalytic degradation activity of methyl orange solution (MOO) under visible light irradiation was investigated. The experimental results show that the structures of the polyacids PW12 and SiW12 in the hybrids remain intact during the precipitation process. It was found that the absorption of the resulting hybrids in the visible region was greatly increased. Under visible light irradiation, compounds TITH-PW12 and TITH-Si W12 could completely degrade the methyl Orange MOA solution without adding any oxidant. The catalyst is easy to be separated and recovered from the reaction system, and its structure and catalytic activity remain unchanged after being reused for four times, and the catalytic degradation satisfies the first-order kinetic equation. When the same Guang Min was used to change the Keggin heteropoly acid, the catalytic activity of the complex formed did not change obviously. Therefore, the selection of Guang Min played an important role in the degradation of dye catalytic activity.
【学位授予单位】：东北师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O644.1

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