碳酸二甲酯活化形态及基于双酚A的反应机理研究

发布时间：2018-04-29 03:08

本文选题：聚碳酸酯 + 有机氧化锡催化剂　；参考：《天津工业大学》2016年硕士论文

【摘要】：聚碳酸酯(Polycarbonate,简称PC)是一种无色透明的无定形热塑型材料,属于五大工程塑料之一。具有优良的电绝缘、耐热、抗冲击及耐化学腐蚀等特性。随着人们对绿色化学和可持续发展的日益关注,PC的生产工艺逐渐向着绿色、环保以及高附加值方向发展。本文通过碳酸二甲酯(DMC)酯交换法催化合成PC中间体(MmC(1)和DmC(1)),对合成过程中使用的催化剂结构与催化效果进行研究,探索其催化机理,得出结论如下：首先,通过TG-MS和In situ DRIFTS研究了非均相催化剂管状和锐钛Ti02的催化机理：DMC在催化剂表面的活化形态是决定酯交换和烷基化反应的关键因素。其次,采用格式试剂法合成了一系列均相有机氧化锡催化剂：苯基氧化锡2(三氟甲苯)氧化锡((PhCF3)2SnO)和二甲苯基氧化锡((PhCH3)2SnO),杂环氧化锡二吡啶基氧化锡((C5H4N)2SnO),二噻吩基氧化锡((C4H3S)2SnO)和二呋喃基氧化锡((C4H3O)2SnO)。对催化剂结构进行系统表征,结合GC对合成的PC中间体选择性进行研究,探究各个催化剂的催化效果：在苯基氧化锡中,转化率方面,(PhCF3)2SnO＞Ph2SnO (PhCH3)2SnO, BPA转化率最高可达42.83%；MmC(1)选择性方面,Ph2SnO (PhCH3)2SnO (PhCF3)2SnO, MmC(1)产率最高可达93.33%。在杂环氧化锡中,(C4H3O)2SnO催化性能最好,BPA转化率可达75.40%,MmC(1)选择性为49.08%。然后,利用TG-MS, In situ DRIFTs和计算机模拟方法研究均相催化剂的反应机理：Sn=O和DMC之间的结合模式是决定酯交换反应和烷基化反应的关键因素。DMC的CH3-O部分的两个氧原子与Sn=O结合,引起C=O键缩短,BPA中的氧原子主要进攻DMC的羰基碳形成酯交换产物；如果DMC的C=O部分的氧原子与Sn=O结合,会引起C=O键伸长,BPA中的氧原子进攻DMC的甲基碳形成烷基化产物。最后,研究了CO2在高温高压条件下对DMC酯交换法的影响：CO2在高压下不仅可通过抑制PC中间体分解抑制烷基化反应,而且可抑制酯交换反应进行。温度对酯交换影响更显著,高温可促进PC中间体分解而促进烷基化反应。
[Abstract]:Polycarbonate polycarbonate (PC) is a colorless and transparent amorphous thermoplastic material, which belongs to one of the five major engineering plastics. Excellent electrical insulation, heat resistance, impact resistance and chemical corrosion resistance and so on. With the increasing attention to green chemistry and sustainable development, the production process of PC is gradually developing towards the direction of green, environmental protection and high added value. In this paper, the catalytic synthesis of PC intermediates MmC1) and DmC1 (DMC) by transesterification of dimethyl carbonate (DMC) was carried out. The structure and catalytic effect of the catalysts used in the synthesis were studied, and the catalytic mechanism was explored. The conclusions are as follows: firstly, The catalytic mechanism of heterogeneous catalyst, tubular and anatase Ti02, was studied by TG-MS and in situ DRIFTS. The activation morphology of Ti02 on the catalyst surface was the key factor to determine the transesterification and alkylation reaction. Secondly, A series of homogeneous organotin oxide catalysts were synthesized by format reagent method: phenyl tin oxide 2 (trifluorotoluene) tin oxide (PhCF3 + 2SnO) and xylene tin oxide (PhCH3 + 2SnO), heterocyclic tin oxide dipyridyl tin oxide C5H4N0 2SnO, dithiophene tin oxide C4H3Sf2SnO) and dithiophene tin oxide. C _ 4H _ 3O _ (2) SnO _ (2). The structure of the catalyst was systematically characterized, and the selectivity of the synthesized PC intermediate was studied in combination with GC. The catalytic effects of each catalyst were investigated: in phenyltin oxide, In the aspect of conversion, the highest conversion rate of Ph2SnO is 42.83% (MmC1). In the aspect of selectivity, the highest yield of Ph _ 2SnO _ (2) C _ (3) C _ (3) O (M _ (mc) ~ (1) can reach 93.33%. The catalytic activity of C _ 4H _ 3O _ 2SnO in heterocyclic tin oxide is the best, the conversion of BPA can reach 75.40 and the selectivity of MmCf-1) is 49.08. Then, TG-MS, In situ DRIFTs and computer simulation were used to study the reaction mechanism of homogeneous catalyst: Sno O and DMC. The two oxygen atoms in the CH3-O part of DMC combined with Sn=O, which were the key factors determining the transesterification and alkylation reaction. The oxygen atoms in DMC mainly attack the carbonyl carbon of DMC to form transesterification products, and if the oxygen atoms in DMC C / O part are bound with Sn=O, the oxygen atoms in C / O bond can attack the methyl carbon of DMC to form alkylation products. Finally, the effect of CO2 on the transesterification of DMC under high temperature and high pressure was studied. At high pressure, the alkylation reaction was inhibited by inhibiting the decomposition of PC intermediate, but also the transesterification reaction was inhibited. The effect of temperature on transesterification is more obvious. High temperature can promote the decomposition of PC intermediates and the alkylation reaction.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ323.41;O643.36

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