【作者】 张子恒；

【导师】 邢彦军；

【作者基本信息】 东华大学 ， 纺织化学与染整工程， 2012， 硕士

【摘要】 聚对苯二甲酸乙二醇酯是一种优良的聚酯材料,在诸多领域如饮料瓶、纤维、薄膜等领域中都有应用。但随着PET产业的快速发展和产品的广泛使用,产生大量的PET废弃物。降解PET废弃物的传统方法需要大量浓酸或浓碱,且催化剂不能重复回用,设备腐蚀和污染现象严重。离子液体是一类极具应用前景的环保型溶剂及催化剂,不挥发、对水和空气稳定,对许多高分子材料具有良好溶解性及催化降解性。另外,微波加热法可极大促进有机反应。本论文采用微波加热法合成了若干种离子液体,并选取其中一种离子液体,在微波条件下对废弃的PET进行催化降解并回收对苯二甲酸,为废弃PET的降解提供了新的方法与思路。主要研究内容如下：首先,在微波条件下,以氯化1-丁基-3-甲基咪唑([Bmim]Cl)、氯化锌为原料,合成离子液体1-丁基-3-甲基咪唑氯锌酸盐,并与常规合成方法进行对比。同时考察了溶剂对离子液体合成的影响。结果表明：运用微波法合成离子液体的效率远高于常温合成法；所用溶剂对离子液体的合成产率影响较大；不同原料比对所合成离子液体的化学结构影响不大；原料摩尔比为[Bmim][Cl]:ZnCl2=1:2时,合成的产率最高。以合成的离子液体1-丁基-3-甲基咪唑氯化锌盐为催化剂,醇解聚对苯二甲酸乙二醇酯(PET),回收生成的对苯二甲酸(TPA)。考察了离子液体的合成条件、离子液体加入量、溶剂加入量、降解温度、降解反应时间等因素对离子液体降解效果的影响。结果表明：(1)合成的离子液体可有效的催化降解PET,且对TPA的回收率可达20%左右。微波法与常温合成法制备的离子液体具有相同降解效果；使用不同溶剂合成的离子液体对PET的降解效果差异不大。本实验成功的从聚酯降解产物中回收了对苯二甲酸,且纯度较高；随着离子液体加入量的增加,对苯二甲酸的回收率反而会降低；降解反应中,增加溶剂乙二醇的用量不会对对苯二甲酸的回收率产生明显影响；降解温度越高,聚酯的降解效果越好；随着反应时间的延长,TPA的回收率会增加,但回收率有极限值。运用常规常温合成法或微波反应合成法合成了氢氧化1-丁基-3-甲基咪唑,测定合成产率并运用指示剂滴定法、电位滴定法对其羟基含量进行了测定。结果表明：以环己烷为溶剂合成氢氧化1-丁基-3-甲基咪唑时,随着反应物中KOH比例的增加,离子液体产率呈先增加后减少的趋势；随着常温合成反应时间的延长,合成离子液体的产率逐渐下降；生成的离子液体中的羟基含量与理论值较接近,大约都在21%左右；电位滴定法滴定离子液体所得结果与指示剂滴定法所得结果差异较大。同时,合成了1-丁基-3-甲基咪唑氯锡酸盐,并考察了合成溶剂、原料摩尔比例、加热条件对合成产率的影响。1-丁基-3-甲基咪唑氯锡酸盐离子液体中不能存在水分；变化原料比例来合成1-丁基-3-甲基咪唑氯锡酸盐离子液体不会影响到离子液体阳离子部分的化学结构。更多还原

【Abstract】 Polyethylene terephthalate is a kind of excellent polyester material, it is applied in many fields, such as beverage bottle, fibre, thin film and so on. However, due to the rapid growth of PET industry and the wide appliance of PET product, lots of PET waste is produced. The conventional method of depolymerization of PET needs a large quantity of concentrated acid or alkali as catalyst, which can’t be reused. Moreover, the appratus is seriously corroded and contaminated.Ionic liquid is a kind of environment-friendly solvent and catalyst which has a good prospect of appliance, property of non-volatile and stability to water and air. It can dissolve or depolymerize many macromolecular material.Microwave-assisted method can promote organic reaction significantly. In this paper, ionic liquids were first synthesized by microwave-assisted synthesis method. A new method for the depolymerization of PET was developed by using synthesized ionic liquids. During the depolymerization, terephthalic acid was recovered. The main conclusions are given as follows:A series of ionic liquid of 1-butyl-3-methylimidazolium zinc chloride was synthesized by 1-butyl-3-methylimidazolium chloride and zinc chloride using microwave-assisted synthesis method which is then compared with the reported synthesis method. The influence of solvents on the synthesis of ionic liquid was also investigated. The results show that the synthesis of ionic liquid by microwave-assisted synthesis method is much more efficient than that by normal synthesis method. The influence of solvents on the productivity of ionic liquid was notable. The chemical structure of ionic liquid synthesized is not influenced significantly by different reactant ratio and a highest yield can be obtained when the reactant ratio [Bmim][Cl]:ZnC12=1:2.PET was alcoholyzed to recover terephthalic acid (TPA) using the synthesized ionic liquid as catalyst by microwave-assisted method. The influence of the synthesis-condition, dosage of ionic liquid, dosage of solvent, reacting temperature and reacting time on the depolymerization of PET was studied. The results show that the synthesized ionic liquid can catalyze and depolymerize the waste PET effectively. The recovery coefficient of terephthalic acid can reach up to approximately 20 percent. The ionic liquids prepared by microwave method have the same depolymerizing effect as the ionic liquid prepared by the reported synthesis method. The differences among the depolymerizing effects of the ionic liquids synthesized by different solvents are not significant.This experiment has successfully recover terephthalic acid which has a high purity from PET-depolymerizing product. As the increase of the dosage of ionic liquid, the recovery coefficient decreases. During the depolymerization reaction, the increase of dosage of glycol will not affect the recovery coefficient of terephthalic acid apparently. Higher depolymerizing temperature makes a better PET-depolymerizing effect. The recovery coefficient of TPA will increase with the increase of reaction time, but it has a limit value.1-Butyl-3-methylimidazolium hydroxide was synthesized using the reported synthesis method and microwave-assisted method. The content of the hydroxyl radicals was detennined by indicator titration method and electric potential titration method. The results showed that when 1-butyl-3-methylimidazolium hydroxide was synthesized using cyclohexane as solvent, the yield of the ionic liquid increases first and then decreases as the enhance of the proportion of the potassium hydroxide in the reactants. The yield of the ionic liquid decreases gradually as the normal temperature synthesis reaction time lengthened. The content of hydroxyl radicals in the synthesized ionic liquids is fairly approaching the theoretical value, approximately 21 percent of the total weight. The result of titrating ionic liquid using potential titration method is very different from that of using indicator titration method.Meanwhile,1-butyl-3-methyl- imidazolium stannum chloride was synthesized. The influence of solvent, reactant ratio and heating method on synthesis yield was studied. The synthesized 1-butyl-3-methyl-imidazolium stannum chloride should be kept from moisture. The change of reactant ratio in the synthesis of 1-butyl-3-methylimidazolium stannum chloride did not affect the chemical structure of its cationic part.更多还原